Method and apparatus for alignment optimization with respect to plurality of layers for writing different layers with different machine configurations

ABSTRACT

A method of patterning a plurality of layers of a work piece in a series of write machines, wherein errors due to different transformation capabilities of different machines are compensated by distributing the errors over the plurality of layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional U.S. patent application claims priority under 35U.S.C. §119(e) to provisional U.S. patent application No. 61/282,561,filed on Mar. 1, 2010, provisional U.S. patent application No.61/282,547, filed on Feb. 26, 2010, provisional U.S. patent applicationNo. 61/323,047, filed on Apr. 12, 2010, provisional U.S. patentapplication No. 61/323,048, filed on Apr. 12, 2010, and provisional U.S.patent application No. 61/323,685, filed on Apr. 13, 2010, the entirecontents of all of which are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to laser pattern imaging ofworkpieces in the manufacturing of products comprising patterning of aphotosensitive surface employing a laser direct imaging device. Moreparticularly, the present invention relates to methods and apparatusesfor performing pattern alignment with respect to patterns in a pluralityof layers for writing different layers with different machineconfigurations.

GENERAL BACKGROUND OF THE INVENTION

It is common practice to manufacture printed circuit boards in a methodto build a sequence of layers having different electric circuitpatterns. For this purpose pattern generators using a laser directwriter as an imaging device for writing an electric circuit pattern on asubstrate are well known.

For example in the manufacturing of printed circuit boards withintegrated circuits, a plurality of dies in the form of small blocks ofsemiconducting material each having a functional electronic circuit aredistributed on a printed circuit board workpiece e.g. in the form of acarrier silicon wafer. The dies are then covered with further layers ofmaterial to form the integrated circuit in a series of manufacturingsteps. In the course of the manufacturing process patterns are generatedon selected layers of the workpiece in one or a plurality of patterningsteps.

Pattern Generation

Patterns are generated on a layer of a workpiece, for example for thepurpose of forming an electric circuit pattern generated in order tocouple connection points or contact pads of components such as dies in adesired electric circuit. The expression die is herein used as commonexpression for any electronic component such as a passive component, anactive component, or any other component associated with electronics.Such a pattern is generated in a writing or printing process in which animage of a circuit pattern is projected, written printed on a surfacelayer covering a conductive layer on the workpiece.

In this context writing and printing are to be understood in a broadsense. For example, projecting, writing or printing a pattern on asurface may include exposing a photoresist or other photosensitivematerial, annealing by optical heating, ablating, creating any otherchange to the surface by an optical beam, etc.

Dependent on the used kind of photosensitive surface material, unexposedor exposed parts of the photosensitive surface layer are removed to formetching masks on the workpiece. The masked workpiece is then etched toform the desired electrical circuit pattern on the conductive layer. Avariation of this concept is to use the pattern to deposit material ontothe underlying layer, e.g. to form an electrical circuit pattern orconnection points on the workpiece.

Pattern Generator

The pattern generator is for example realized by means of a laser directimaging (LDI) system devised for writing a pattern on the photosensitivesurface by means of a laser scanning the surface with a laser beam thatis modulated according to image pattern data and forming an imagerepresenting a desired electrical circuit pattern.

SPECIFIC BACKGROUND OF THE INVENTION

In recent development of manufacturing methods in this field theinterest for embedded dies technologies and wafer level packagingtechnologies has increased due to expected advantages in cost andperformance. Although these are referred to as different technologiesthey both involve the embedding of dies and related problems.

In this development of manufacturing integrated circuits and otherproducts involving patterning of layers there are however variousfactors that affect the productivity. The placing of dies and alignmentof patterns are important factors that are decisive for the overallyield in the manufacturing process using these technologies. Forexample, in wafer level packaging the fan-out process comprise stagesthat are limiting to productivity.

Alignment and Overlay Control

The printed patterns must be aligned to certain features of theworkpiece, for example to the dies in order to fit to connection pointsin the functional electronic circuit of the respective die or to otherpatterns in the same or different layers of the workpiece. Overlaycontrol is a term describing the monitoring and control ofpattern-to-pattern alignment on multilayer structures.

In prior art, measuring systems comprising imagers e.g. CCD cameras, arecommonly used in such alignment procedures for determining the positionof a workpiece and selected features on the workpiece. For example, thecameras are employed to detect features of the workpiece such as edgesor markings on the workpiece, the positions of the features in theimages are used to calculate the real physical positions in relation toa reference in the pattern generator. There are different ways tocompensate for the deviations of the real physical conditions from theideal physical conditions upon which the originally designed imagepattern data is assumed. For example, the image pattern data is adjustedand then the pattern is written dependent on the adjusted image patterndata. In another example, the coordinate system of the writer isadjusted to compensate and the original pattern data is written in anadjusted coordinate system.

Placing of Dies on Workpiece

Prior art patterning systems require workpieces with dies placed veryaccurately on the workpiece to be able to align patterns to the dies.This is due to the fact that prior art patterning systems use steppersand aligners that have limited capabilities to perform alignment toindividual dies without significantly slowing down the patterningprocess with the consequence that current requirements on the takt timethat sets the pace for the process of manufacturing products comprisingpatterned layers cannot be met. In prior art, the dies are accuratelyplaced on the workpiece and fastening the dies by eutectic bonding orglue onto the workpiece, which is a very time consuming process.

Placing of Dies on Workpiece by Pick-and-Place Machine

There is a desire in the industry to distribute the dies on theworkpiece by means of a pick and place machine in order to increase theproduction rate. However, present day pick-and-place machines cannotkeep the speed required by the takt time of the manufacturing process,while maintaining the placement accuracy that is required by prior artpattern generators to manage alignment. Dies placed by means ofpick-and-place machines can be regarded to have random positionalerrors.

Fan Out Process

The fan out process is an example of a process that includes arrangingconductive paths for connecting to connection points of dies on aworkpiece. A redistribution layer covering the dies is provided with acircuit pattern that is aligned with the dies and connected to contactpads e.g. with solder balls deposited on the redistribution layer andextending to an another layer in a vertical electrical connection by anaperture that in short is called a via, for vertical interconnect accessbetween conductors in different layers. Typically, the connection pointsor the connection lines are spread over a larger surface area in toenable a higher ball grid pitch. Alignment between layers is animportant factor in the fan-out process and prior art conventionalfan-out processes for inaccurately placed dies are not cost effectivedue to the poor performance of alignment to individual dies in prior artpatterning systems. FIG. 1 shows schematically an example of embeddeddies in a prior art process description of a fan-out wafer levelpackaging process. This process is further described in the detaileddescription below.

PRIOR ART

Examples of prior art pattern generators and alignment are found in thepatent publications:

US 2003/0086600 Multilayer Printed Circuit Board Fabrication System andMethod;

WO 03/094582 and related US2005/0213806 (A1) A System and Method forManufacturing Printed Circuit Boards Employing Non-uniformly ModifiedImages.

These pieces of prior art describe the general functionality of patterngenerators in the form of laser direct imaging systems adapted to writean electric circuit pattern on a printed circuit board dependent onpattern image data. These publications further describe prior art foralignment of patterns on substrates.

Difficulties in Prior Art

FIG. 2 shows an example of dies 202 placed on a workpiece in the form ofa wafer 200 in a general order on a global level but in a non-systematicorder on a local level. In summary, in order to increase production ratedie placement must be allowed to be less accurate and evennon-systematic as in FIG. 2. However, random positional errors for a diemake it relatively difficult to achieve desired overlay performance withconventional aligners. In prior art, EGA alignment (Enhanced GlobalAlignment) capability allows conventional stepper technology to increaseexposure rate in packaging of devices with relatively tight designrules. In this case such steppers expose the same transform of patternfor several dies in the assumption that they fit to the same transform.Alternatively, the same pattern is exposed for such a low number of diesthat the probability of excessively large deviations from specificationis avoided.

FIG. 3 shows a conventional prior art printing method that seeks to dealwith the local alignment problem, here aligning to individual dies 300in a group of two dies. As shown in FIG. 3, the exposure regions aredivided into small areas down to each die. In A. 1×1 field with 2drop-in die which in this example requires 390 exposure shots/wafer; inB. 2×2 filed overprinting at edge and requiring 103 shots/wafer; and inC. 5×3 field overprinting at edge 34 shots/wafer. The exposure is inthis prior art method performed by steppers. However, this conventionalapproach has a relatively large takt penalty because realigning for eachshot is necessary.

Examples of prior art describing alignment between different layers areinter alia shown in the patent publications:

WO2010049924(A1) to Orbotech [P19, U.S. Pat. No. 7,508,515(B2) [P13] andWO2004109760(A2) to Sony [P20] show examples of transformation ofpattern of subsequent layer to actual pattern of previous layer, e.g.transforming contact pads. However, this piece of prior art lacksdisclosure of application in stack with dies and solutions addressingspecific problems in this application.

In the fan-out process or similar processes, such as embedded dieprocess, where a number of connection lines from two or more dies are tobe connected there may still be problems after alignment of the patternto the dies. FIG. 12 illustrates connection lines 1506 from two dies1502, 1504 in the ideal design domain, typically CAD (computer aideddesign) domain. The respective connection lines are connected inconnection points 1508.

FIG. 13 illustrates how the result may look in reality after the patternhas been aligned to each die 1502,1504 or other component according toprior art. With transformation of a pattern to individual diesdifferences in the individual transformations may create edge roughnessor even bad connections for lines in the pattern that are intended toconnect dies to each other or to other layers. As illustrated in FIG.13, many of the connection points 1508 are not connected. This makes itunsuitable or even impossible to individually align to each die with thenormal current quality requirements. The connection points in thepattern portions comprising the connection points 1508 are clearlymisaligned.

PROBLEM

The general object of the invention is to provide a method forperforming alignment of patterns in different layers to be written withdifferent writing machine configurations. An aspect of this problem isto optimize the alignment to achieve an improved accuracy of patterns.More particularly, the present invention relates to methods andapparatuses for performing pattern alignment with respect to patterns ina plurality of layers.

SUMMARY OF THE INVENTION

The general object is achieved and the problem is solved by providing amethod and/or an apparatus and/or a computer program product accordingto the appended claims.

The invention is applicable to laser pattern imaging of workpieces inthe manufacturing of products comprising the patterning of a surfaceemploying a laser direct imaging device. For example, patterning byprojecting, writing or printing a pattern on a surface may includeexposing a photoresist or other photosensitive material, annealing byoptical heating, ablating, creating any other change to the surface byan optical beam, etc.

Examples of such products are printed circuit boards PCB, substrates,flexible roll substrate, flexible displays, wafer level packages WLP,flexible electronics, solar panels and display. The invention isdirected to patterning such a photosensitive surface on a workpiece forsuch products with dies in a direct write machine, where a workpiece canbe any carrier of a surface layer upon which a pattern can be printedwith a laser direct imaging system.

According to the invention, the problem is solved by compensating forerrors due to different transformation capabilities of differentmachines by distributing the errors over the plurality of layers. Theinvention solves the problem aspect of minimizing the errors that mayoccur from layer to layer, and may be applied on workpiece having or nothaving embedded dies.

The invention is employed in a method, system of apparatus and/or acomputer program product configured for patterning a plurality of layersof a work piece for example in a direct write machine.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be further explained with reference to theaccompanying drawings wherein:

FIG. 1 shows schematically an example of embedded dies in a prior artprocess description of a fan-out wafer level packaging process.

FIG. 2 shows schematically an example of a workpiece with diesdistributed thereon.

FIG. 3 shows schematically an example of a prior art method for aligningto individual dies or to a group of dies.

FIG. 4 shows schematically an example of an alignment mark on a die.

FIG. 5A-B show schematically an example of local pattern adaptation toindividual dies in accordance with an embodiment the invention.

FIG. 6 shows a flow diagram of a method according to an embodiment ofthe invention.

FIG. 7 shows schematically an example of adjustment of a localcoordinate system in accordance with an embodiment of the invention.

FIG. 8 shows schematically an example of a workpiece with diesdistributed thereon, illustrating the local and global location andorientation of dies dependent on the shape of the workpiece.

FIG. 9A shows a flow diagram of a method of alignment of pattern to diesaccording to an embodiment of the invention.

FIG. 9B shows schematically a block diagram illustrating embodiments ofapparatus for patterning a workpiece in accordance with the invention.

FIG. 9C illustrates an example of a 3D system in package.

FIG. 10A illustrates an example of how a part of a pattern is connectedto connection points of dies in a top view of a work piece.

FIG. 10B illustrates a side view of the example in FIG. 10A.

FIG. 11A-B illustrates in top view and side view how dies in a firstwork piece layer is overlayed with dies in a second layer of same ordifferent work piece.

FIG. 11C shows a flow diagram of alignment of pattern to features in aplurality of layers.

FIG. 12 illustrates a pattern in the design (CAD) domain.

FIG. 13 illustrates an example after a pattern has been adjusted to thetransformation of each die.

FIG. 14 is an illustration of identified sacred regions and stretchregions.

FIG. 15 illustrates another pattern in the CAD domain.

FIG. 16A illustrates a pattern without using the stretch zone conceptand in which only individual transformations are applied to the pattern.

FIG. 16B illustrates an example pattern when the stretch zone concept isused to reconnect regions that are connected in the ideal (original)coordinate system using a linear connection between the sacred zones.

FIG. 17A illustrates an example pattern without using the stretch zoneconcept and in which only individual transformations are applied to thepattern.

FIG. 17B illustrates an example pattern when the stretch zone is used toreconnect regions that are connected in the ideal (original) coordinatesystem using a linear combination between the individualtransformations.

FIG. 18 illustrates an example in which an additional zone has beenidentified or marked either automatically by the machine or in thepattern file.

FIG. 19A illustrates an example in which a third zone is not applied.

FIG. 19B illustrates an example in which a third zone is applied.

FIG. 20A shows an example printed pattern without compensation.

FIG. 21A-21B show example transformation maps.

FIG. 22A shows an example printed pattern with compensation.

FIG. 22B shows a flow chart of a method employing the sacred zoneconcept according to an embodiment of the invention.

FIG. 23 illustrate example transformations.

FIG. 24A illustrates the placement of dies in a first layer.

FIG. 24B-C illustrate a pattern in a second layer and in an Nth layeraligned with the dies in the first layer of FIG. 24A.

FIG. 25 illustrates the sequence of transformations of patterns througha plurality of layers.

FIG. 26 illustrates reference positions for dies.

FIG. 27 illustrates a cross-section view of a workpiece with a pluralityof layers.

FIG. 28 illustrates a cross-section view of a workpiece with a pluralityof layers.

EXPLANATIONS OF TERMINOLOGY AND EMBODIMENTS USED IN THIS TEXT

Workpiece

For the purpose of this application text the term workpiece is used todenominate any carrier of a surface layer upon which a pattern can beprinted with a laser direct imaging system. For example a siliconsubstrate or a silicon wafer for a printed circuit board workpiece, oran organic substrate. Workpieces may have any shape, such as circular,rectangular or polygonal, and may have any size for example in a pieceor in a roll.

Die

For the purpose of this application text the term die is used todenominate a passive component, an active component, or any othercomponent associated with electronics. For example, a die may be a smallblock of material, on which a given functional circuit is fabricated.

Local Alignment

For the purpose of this application text the term local alignment isused to denominate alignment in relation to alignment features, forexample alignment marks, on an individual die or on a group of dies.

Global Alignment

For the purpose of this application text the term global alignment isused to denominate alignment in relation to alignment features, forexample alignment marks, on a workpiece.

Various Explanations

In the drawings, the thicknesses of layers and regions are exaggeratedfor clarity. Like numbers refer to like elements throughout thedescription of the figures.

Detailed illustrative embodiments are disclosed herein. However,specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Exampleembodiments may be embodied in many alternate forms and should not beconstrued as limited to only the example embodiments set forth herein.

It should be understood, however, that there is no intent to limitexample embodiments to the particular ones disclosed, but on thecontrary example embodiments are to cover all modifications,equivalents, and alternatives falling within the appropriate scope.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and/or,” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being“connected,” or “coupled,” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected,” or “directly coupled,” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between,” versus “directly between,” “adjacent,” versus“directly adjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an,” and “the,”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises,” “comprising,” “includes,” and/or “including,” whenused herein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Example embodiments relate to scanning of workpieces, such as asubstrate or wafer, for reading and writing patterns and/or images.Example embodiments also relate to measuring workpieces. Examplesubstrates or wafers include flat panel displays, printed circuit boards(PCBs), flexible printed circuit boards (FPBs), flexible electronics,printed electronics, substrates or workpieces for packagingapplications, photovoltaic panels, and the like.

According to example embodiments, reading and writing are to beunderstood in a broad sense. For example, reading operations may includemicroscopy, inspection, metrology, spectroscopy, interferometry,scatterometry, etc. of a relatively small or relatively large workpiece.Writing may include exposing a photoresist or other photosensitivematerial, annealing by optical heating, ablating, creating any otherchange to the surface by an optical beam, etc.

DETAILED DESCRIPTION OF EMBODIMENTS

The invention is embodied in methods, apparatus and computer programproducts for patterning a workpiece.

Operating Environment of the Invention

The invention is typically employed in a scanning laser direct imaging(LDI) system comprising for example a laser direct writer as describedin the above mentioned prior art publication US 2003/0086600, which ishereby incorporated by reference as an example of such a machine thatmay be used for the implementation of embodiments of the invention. Insuch a system a laser beam is scanned over a photosensitive surfacelayer of a workpiece to expose the layer with a pattern in accordancewith pattern image data. Different embodiments of the invention mayinclude patterning equipment for example for patterning by projecting,writing or printing a pattern on a surface that may include exposing aphotoresist or other photosensitive material, annealing by opticalheating, ablating, creating any other change to the surface by anoptical beam, etc.

The system preferably comprises a computer adapted to control thepatterning, e.g. laser beam scanning, dependent inter alia on imagepattern data that may be adjusted, compensated or transformed. Thesystem further comprises or is coupled to a computerized measuringsystem, typically having CCD cameras and recognition software devised torecognize objects such as dies or features such as alignment marks on aworkpiece. Measurement data from the measuring system is used in analignment system to adapt original image pattern data in order tocompensate for deviations in the workpiece from assumed conditions. Whenimplementing the invention a computer is provided with specificallydesigned computer programs adapted to perform steps of the inventivemethod.

The invention is devised to operate on a workpiece, for example asilicon substrate, an organic substrate or a wafer, that is providedwith dies distributed and placed with an arbitrary position on theworkpiece. The positions of the dies are defined in a three-dimensionalcoordinate system and thus indicate location and orientation. Forexample, the dies may have been placed on the workpiece by means of apick-and-place machine, resulting in a workpiece with low positionaccuracy of the dies. The dies shall typically be aligned with a circuitpattern to be printed on a surface layer such that the circuit patterncan be connected to connection points of the dies, for example in afan-out process. Preferred embodiments are implemented in or inconjunction with a direct write machine and alignment system.

Example of Fan-Out Process

FIG. 1 shows schematically an example of embedded dies in a prior artprocess description of a fan-out wafer level packaging process. Such aconventional FAN-out process, here exemplified with a prior art fan-outwafer level packaging known to be provided by Infineon (Source:Infineon), typically comprises the following steps:

-   Step 1: A laminate carrier, for example a carrier wafer, is provided    and arranged to receive dies on an adhesive tape.-   Step 2: A plurality of dies (of one or several types) are placed on    the carrier by means of a pick and place machine.-   Step 3: Compression moulding over the dies and the adhesive tape to    fixate the dies in a moulded carrier wafer.-   Step 4: Separating the carrier from the adhesive tape and the    moulded carrier wafer.-   Step 5: Removing, for example by pealing, adhesive tape from the    moulded wafer to create a reconstituted wafer.

After placing the dies on the moulded carrier wafer, one or morepatterning steps are performed on the wafer, for example a selection of:

-   Step 6: Deposition and patterning of dielectric, possibly a multiple    of this step.-   Step 7: Metallization and patterning.-   Step 8: Deposition and patterning of dielectric.-   Step 9: Solder bump deposition to achieve electric connection for    external terminals to contact pads coupled to connection points of    dies.

An embodiment of the present invention is adapted to be applied foralignment in the patterning steps in this kind of fan-out process inorder to improve cost efficiency.

Workpiece with Arbitrarily Placed Dies

As briefly mentioned in the background section FIG. 2 showsschematically an example of a workpiece 200 with a plurality of dies 202distributed thereon, in this example a reconstituted wafer in an eWLBpackaging structure, where eWLB is an abbreviation for embedded WaferLevel Ball Grid Array. As shown in FIG. 2, conventionally, die placementis non-systematic, and a printed field, i.e. a field of printed circuitpattern will have different registration errors in relation to differentdies and in practice a workpiece produced like this will have randompositional errors. The invention is adapted to enable local alignment ofpatterns to embedded dies for example in this kind of workpiece.

The workpiece that the invention is intended to operate on has aplurality of dies distributed thereon. It is assumed that the dies aredistributed and positioned arbitrarily or randomly on the workpiece,although the dies would normally be placed in a general global order onthe workpiece. The positions of the dies would also normally be affectedby the shape and shape deviations of the workpiece. FIG. 8 shows anexample of a workpiece in the form of a wafer with the local and globallocation and orientation of dies thereon. To the left there is anoriginal workpiece, in the form of a wafer, from a top view 802 and aside view 800. In the middle there is shown a top view 804 and a sideview 808 of a wafer with dies 807 distributed thereon generally orderedand located in rows. To the right there is an illustration of theposition of dies 807 in a 2-dimensional global coordinate system 806 andthe orientation of individual dies 807 in local 3-dimensional coordinatesystems (x,y theta) 808 thus belonging to each individual die. Theposition of each die may include translation, rotation, warpage, etc. Tothe right there is also a side view of the workpiece showing globalwarpage 812 of the wafer and local warpage 810 of the dies.

Embodiments of Method for Patterning a Workpiece

In one variety the invention is embodied in a method for patterning aworkpiece for example in a direct write machine. The workpiece has oneor a plurality of dies distributed thereon. The direct write machine isprovided with a coordinate system for controlling write operations in aper se known manner.

Each die is associated with a circuit pattern in the form of originalcircuit pattern data. This is illustrated in FIG. 5A and FIG. 5B, whichshow schematically an example of local pattern adaptation to individualdies on a workpiece in accordance with an embodiment the invention. InFIG. 5A, a workpiece 500 having global reference marks, for examplealignment marks, is provided with a plurality of arbitrarily placed diesof two different types, die type 1 504 and die type 2 506. FIG. 4 showsschematically aper se known example of a reference mark 402 in the formof an alignment mark on a die 400, in this example the alignment mark isa bright cross 402. The different die types are to be aligned withdifferent pattern types, pattern type 1 508 and pattern type 2 510. FIG.5B illustrates that the pattern type 1 508 has been aligned with andprinted on a layer over die type 2 506, and that the pattern type 2 510similarly has been aligned with and printed on a layer over die type 1504. Further, multiple dies of the same type may have a different typeof pattern. In FIG. 5B, the rotation of the pattern has been adjusted toeach die (cell). In this connection, a die or a group 512 of dies may becalled a cell. It is also possible to have an adjustment for each die(cell) or an adjustment for a group 512 of dies (cells), for example,the same rotation and translation for 3×3 cells.

The workpiece is preferably divided into sub-areas, for example sub-area514 which is associated with a die 504 that in the exemplifyingillustration in FIG. 5B is aligned with pattern 510. A sub-area 516 mayalso be associated with a group 512 of dies.

FIG. 6 shows in a schematic flow diagram an exemplifying embodiment amethod for patterning a workpiece. The method shown in FIG. 6 may beimplemented in a direct write machine, for example.

Referring to the steps in FIG. 6, this embodiment comprises:

At S602: Alignment marks on a workpiece, for example a wafer, or on areference die are measured.

At S604: A position of one or more die(s) on the workpiece (e.g. wafer)is measured. As mentioned above, the position of each die may includetranslation, rotation, warpage, etc. The position of each die may bemeasured in the same machine comprising the direct write machine, or inan external measurement machine. Steps S602 and S604 may be performed inthe reversed order.

If the position of a die is measured in an external measurement machine,the position of the die is relative to some global reference marks onthe carrier wafer or a given reference die. If the measurements areperformed in the direct write machine, the same principle may be used orthe measurements may be used directly in the machine. The position ofeach die is defined in the coordinate system of the writer by measuringthe reference marks and transforming the position and rotation of eachdie to the coordinate system of the machine. Alternatively, thepredefined reference die(s) may be used in the same manner.

Further, according to at least some example embodiments, each die mayhave alignment marks for measurement. Alternatively, each die may bemeasured with some shape-based measurement algorithm capable ofmeasuring the absolute and/or relative position of the die withoutalignment marks, for example, by measuring the shape of the die, themicroscopic non-uniformities and/or characteristics that are inherent toa surface of the die and using these measurements for determining theabsolute and/or relative position of the die. At least one camera (e.g.,a CCD camera or the like) may be used for measuring the shape, features,and/or microscopic non-uniformities of dies or the global workpiece inorder to determine the absolute and/or relative position of the dies.The shape and/or position of the die may also be measured using at leastone sensor (e.g., a physical sensor or the like). According to certainexample embodiments, the position of each die may be measured on thefrontside (e.g., the writing side) of the workpiece and/or on theunderside (e.g., the backside opposite to the writing side) of theworkpiece in combination with (or alternatively without) using alignmentmarks, where the measured shape and/or microscopic non-uniformities ofthe frontside or underside of a workpiece is used as a referenceposition for determining the absolute and/or relative position of a diein or on the workpiece.

As mentioned above, the position of the dies may be determined bymeasuring microscopic non-uniformities, features or a shape of theglobal workpiece (e.g., a corner of the workpiece) that is alsomeasurable in the writer where the measured shape, features and/ormicroscopic non-uniformities of the frontside or underside of theworkpiece is used as a position reference for determining the absoluteand/or relative position of the dies.

At S606: Pattern data is prepared based on the measured alignment marksand position of each die.

At S608: The pattern to be written is re-sampled to fit the position ofeach die. In one example, the pattern is re-sampled from originalpattern data to fit each die. In another embodiment, the pattern israsterized from vector data that have been translated or transformed tofit each die. In an alternative embodiment also mentioned below, thecoordinate system of the writing tool is transformed in a correspondingmanner to fit the original pattern to the positions of the dies, andthen the original pattern is written by the transformed coordinatesystem.

According to example embodiments, different dies may have differenttypes of patterns. As shown in FIG. 5 and explained above, there can beseveral types of dies, and thus, different types of patterns on the samewafer. FIG. 5 is an illustration of how a pattern may be adapted to theposition of a die in these stages of FIG. 6.

At S610: a pattern is written on the wafer, the pattern thus beingadjusted to fit each die.

FIG. 9A illustrates schematically further embodiments of a method forpatterning a workpiece for example in a direct write machine. Theworkpiece has a plurality of dies distributed thereon, where the diesare a selection of a passive component, an active component, or anyother component associated with electronics. The direct write machine isprovided with a coordinate system for controlling write operations in aper se known manner and the method comprises the following steps:

-   902: Receiving measurement data being associated with the workpiece    and indicating a measured position of a plurality of the dies, or    group of dies, distributed on the workpiece in relation to at least    one reference feature of the workpiece. The measurement data is    typically determined by determining a reference feature of the    workpiece, and then measuring the position of the die in relation to    the reference feature.    In different embodiments further described below, the measurement    data file may comprise a list of transformations and areas they    cover, alternatively a measurement file with data that describes the    transformation in a given point. Measurements on dies have been    analyzed in a step before the writer and a high resolution map that    describes the local alignment areas and their values is used in the    writer.

The position of the dies, or group of dies, is preferably determined interms of the location and the orientation of the dies on the workpiecein relation to least one reference; and/or the spatial location andorientation of the dies, or group of dies, in a space comprising theworkpiece in relation to the reference. In a different wording and asexplained above, the position may be indicated as position or locationin a 2-dimensional global coordinate system of the workpiece and theorientation of individual dies in a local 3-dimensional coordinatesystems (x,y theta) thus belonging to each individual die.

A reference feature of a die is for example determined by a selectionof: one or several alignment mark(s) provided on the die; or acharacteristic of the surface structure of the die(s); or acharacteristic of the shape of the die, such as an edge or a corner ofthe die.

As explained above, the measuring of the position of a die is forexample determined by a selection of:

-   a. Determining the spatial position of the die in relation to the    reference feature by means of a selection of a shape based position    determining algorithm, an edge detection based algorithm, a    correlation based algorithm or another image analysis techniques    devised for extracting a position from a reference feature; or-   b. Determining the spatial position of the die in relation to the    reference feature with one or several alignment mark(s) on the die;    or-   c. Determining the spatial position of the die in relation to the    reference feature by a characteristic of the surface structure of    the die.

The measurement data may be determined to indicate the position of thedies or of a group or cluster of dies on the workpiece. The measurementdata may optionally be determined in a separate measurement machine orin a measurement arrangement that is integrated with or integrated inthe direct write machine. The measurement data is preferably received ina computer adapted to manipulate image pattern data and/or to controlthe writing laser beam of the direct write machine.

Further, the measurement data is optionally determined by determining areference feature of the workpiece and/or by measuring the position of agroup of dies in relation to said reference feature. The measurementdata may not necessarily comprise measurement value for every singledie. As mentioned, it is also possible to include measurement values forclusters of for example 2×2 dies, 4×4 dies. The measurement value of acluster may for example indicate an average deviation from a nominalposition.

The reference feature of a die is for example determined by a selectionor a combination of: one or several alignment mark(s) provided on thedie; or a characteristic of the surface structure of the die(s); or acharacteristic of the shape of the die, such as an edge or a corner ofthe die, or by measurement on the writing side or on the backside of theworkpiece.

-   904: Detecting the at least one reference feature of the workpiece,    preferably by detecting means in the form of a measurement system.

The reference features of the workpiece may be detected in a similarmanner as for the detection of reference features for dies as explainedabove, i.e. for example by means of alignment marks on the workpiece, byshape or by other characteristic features on the workpiece or among thedies. In exemplifying embodiments, the at least one reference feature ofthe workpiece is determined by a selection or a combination of one orseveral alignment mark(s) provided on the workpiece; or one or severalreference feature(s) provided on one or a plurality of reference die(s)selected among the plurality of dies;

or a characteristic of the arrangement of the dies distributed on theworkpiece;

or a characteristic of the surface structure of the workpiece; or acharacteristic of the surface structure of the die(s); or one or severalreference die(s); or a characteristic of the shape of the workpiece,such as an edge or a corner of the workpiece; or by measurement on thewriting side or on the backside of the workpiece.

-   906: Determining the relation between the at least one reference    feature of the workpiece and the coordinate system of the direct    write machine. The relation may optionally be measured or be assumed    or be a pre-settable parameter.

The relation that defines how dies are positioned in the direct writemachine comprises using a selection of but preferably all of: theposition of dies, the position of the workpiece and the position of thecoordinate system of the direct write machine.

-   908: Transforming the measured position of the plurality of dies, or    group of dies, distributed on the workpiece to a transformed    position defined in the coordinate system of the direct write    machine dependent on the determined relation between the at least    one reference feature of the workpiece and the coordinate system of    the direct write machine.

Typically, all dies are described by a first transformation in relationto the workpiece, then the workpiece is described by a transformation inrelation to the coordinate system of the writer.

The transformation may further comprise a transformation of the positionand shape of the workpiece to being defined in the writer coordinatesystem. This is true when the workpiece in the measurement stage hasbeen found to have a transformation that deviates from the idealtransformation. In such a case, measurement data for every die iscompensated with the transformation that defines the position of theworkpiece in the measurement machine based on the reference positionused in the writer, which normally would be nominal positions. Thus, inorder to avoid that the different transformations of the workpiece inthe measurement machine and in the writer, respectively, shall affectthe end result.

Determining a Transformation

The transformation to be applied is determined in a variety of ways, forexample dependent on the characteristics of the workpiece and/or thedies distributed thereon.

In one embodiment, the positions of the dies, or group of dies, in termsof both location and orientation on the workpiece together with locationand orientation of the workpiece relative the writer coordinate systemis used to determine a transformation of the measured positions definedin the coordinate system of the direct write machine.

-   910: Preparing adjusted circuit pattern data for writing on the    workpiece dependent both on the original pattern data and the    transformed positions, wherein the adjusted circuit pattern data    represents the circuit pattern of the plurality of dies, or group of    dies such that the adjusted circuit pattern is fitted to at least a    portion of the workpiece area.    Sub-Areas

The adjusted circuit pattern data is in embodiments further renderedsuch that the adjusted circuit pattern is fitted to a plurality ofsub-areas of the workpiece area, possibly wherein each sub-area isassociated with a die, or group of dies, among the plurality of diesdistributed on the workpiece. Further, the adjusted circuit pattern datamay be rendered to be fitted to the plurality of dies, or group of dies,in a way such that the sub-portions of the adjusted pattern data eachrepresents a sub-area of the workpiece associated with a particular die,or group of dies, and where each of said sub-areas includes, or covers,said particular die, or group of dies.

The workpiece may be divided into sub-areas in different ways. In oneembodiment, at least a portion of the workpiece area is divided intosub-areas that each are to be represented by sub-portions of theadjusted pattern data, and wherein the sub-areas are identified by thereceived measurement data and/or the workpiece area is divided intosub-areas by the use of a pre-determined algorithm. In anotherembodiment, the sub-areas are automatically identified by the receivedmeasurement data and/or the workpiece area is automatically divided intosub-areas by the use of the pre-determined algorithm. Further, aplurality of said sub-portions of the adjusted pattern data may berendered to fit to respective sub-area within certain requirementsand/or at least one pre-settable deviation parameter.

For the purpose of preparing adjusted circuit pattern data themeasurement may in one embodiment comprise defining a re-sampling mapfor the whole pattern.

In one embodiment, the preparing of adjusted circuit pattern datacomprises transforming the original pattern data in the form of vectordata to fit each die, or group of dies, and rasterizing said transformedvector data such that the rasterized vector data represents the wholeworkpiece having all of the dies distributed thereon.

In another embodiment, the preparing of adjusted circuit pattern datacomprises in one embodiment rendering the original pattern data from aset of ideal pattern data. An ideal pattern is in this context thelayout and the position of the pattern in the nominal coordinate system,usually a CAD system or similar. Then there is a step of re-sampling theoriginal pattern data dependent on the measured position data of thedie(s) and on the transformed position and shape of the workpiece inorder to fit data to each die on the workpiece in the coordinate systemof the direct write machine. Optionally, there is a step of re-samplingthe original pattern data dependent on measured position data of a groupor a cluster of the dies and on the transformed position and shape ofthe workpiece in order to fit data to each group or cluster on theworkpiece in the coordinate system of the direct write machine.

Preferably, the adjusted circuit pattern data represents the wholeworkpiece having all of the dies distributed thereon.

Requirements and/or Deviation Parameter

The fitting of the adjusted circuit pattern is carried out in differentoptional manners.

For example, a plurality of said sub-portions of the adjusted patterndata are rendered to fit to respective sub-area within certainrequirements or one or more pre-settable deviation parameters. Thecertain requirement or pre-settable deviation parameters are, indifferent embodiments, associated with at least one of: a. type of die,component, or group of dies/components; or b. a characteristic of thesurface structure of the die(s)/component(s); or c. a characteristic ofthe shape of the die(s)/component(s), such as an edge or a corner of thedie(s)/component(s).

In one embodiment, the whole adjusted circuit pattern data is fitted tothe plurality of dies, or group of dies, on the workpiece within apre-settable deviation parameter or set of deviation parameters. Thedeviation parameter can be defined in different ways, for example with apre-settable: value, minimum threshold value, maximum threshold value,interval of values or selectable formula for calculating the deviationparameter.

The pre-settable deviation parameters may include both parameter(s)associated with location and parameter(s) associated with orientation.

For example, in one embodiment the deviation parameter is the residualerror of the placement or position of the adjusted circuit pattern inrelation to the dies is in the range of or less than 100 micrometers(μm). In other embodiment the residual error is in the range of or lessthan 10 micrometers (μm), in the range of or less than 5 micrometers(μm), or probably most frequently in the range of or less than 1micrometer (μm). Thus, in different embodiments, the adjusted circuitpattern data is fitted to the plurality of dies, or group of dies, onthe workpiece within a the pre-settable deviation parameter that is setto less than 100 μm or less than 10 μm or less than 5 μm or less than 1μm, for at least some of the dies, or group of dies, distributed on theworkpiece.

A deviation from a perfect fitting or match occurs for example if thereare a plurality of transformations that must coexist simultaneously inthe same area, in this context called a transition zone. In anotherexample, a deviation occurs when the required transformation is a morecomplex transform than that or those available to apply.

The adjusted circuit pattern data associated with a particular die, orgroup of dies, is for example fitted individually to said particulardie, or group of dies. Preferably, the plurality of dies, or group ofdies, includes all of the dies distributed on the workpiece. In oneembodiment, the circuit pattern data associated with at least one of thedies, or group of dies, on the workpiece is adjusted individually andindependently of circuit pattern data associated with the other dies onthe workpiece. In another embodiment, the circuit pattern dataassociated with each of the dies, or group of dies, on the workpiece isadjusted individually and independently of circuit pattern dataassociated with any of the other dies on the workpiece.

The preparing of adjusted circuit pattern data comprises in oneembodiment rendering the original pattern data from a set of idealpattern data. An ideal pattern is in this context the layout and theposition of the pattern in the nominal coordinate system, usually a CADsystem or similar.

Then there is a step of re-sampling the original pattern data dependenton the measured position data of the die(s) and on the transformedposition and shape of the workpiece in order to fit data to each die onthe workpiece in the coordinate system of the direct write machine.Alternatively, there is a step of re-sampling the original pattern datadependent on measured position data of a group or a cluster of the diesand on the transformed position and shape of the workpiece in order tofit data to each group or cluster on the workpiece in the coordinatesystem of the direct write machine.

-   912: Writing a pattern on the workpiece according to the adjusted    circuit pattern data.

In a further development the measurement data is received and the steps904-910 are performed in a sequence, thereby enabling measurement andwriting in real time. Preferably, preparing of adjusted circuit patterndata is based solely on measurements and data associated with theworkpiece, thereby enabling measurement and writing time in real time.

Different Transformation Options

In different embodiments of the invention there are different optionaltransformations.

The transformation of the pattern data, vector data or coordinate systemto fit the spatial positions of the die(s) or groups/clusters of diescould be either linear or non-linear, such as e.g. a spline, polynomialor projective. Similarly, transforming the measured positions totransformed positions of the dies, i.e. single dies or group of dies,comprises a selection of linear or non-linear transformation. Further,the preparation of adjusted circuit pattern data comprises transformingof the pattern data to fit the positions of the dies, or group of dies,may comprise using a selection of linear or non-linear transformation.

Examples of optional, global or local, transformations according todifferent embodiment comprise a selection or a combination of: scale,rotation, mean only; affine transformation; projective transformation;bilinear interpolation, spline, polynomial.

Transformation of Coordinate System in Direct Write Machine

The inventive concept can also be applied in an embodiment where thecoordinate system of the direct write machine is transformed to fit eachdie instead of re-sampling or re-rasterizing data. In other aspects thisembodiment includes the features described above.

FIG. 7 illustrates a workpiece similar to that of FIG. 5A and FIG. 5Band the coordinate system of the direct write machine being transformedto fit to the global workpiece in 708 and to individual dies in 702,704, 706.

In summary this embodiment comprises a method for patterning a workpieceprovided with dies in a direct write machine, wherein measurement dataof positions of the dies in terms of location and orientation is used todetermine a transformation of the coordinate system of the direct writemachine such that a predetermined circuit pattern is fitted to eachrespective die. The predetermined pattern data is written on theworkpiece according to the transformed coordinate system of the directwrite machine.

In more detail such an embodiment would comprise a method for patterninga workpiece in a direct write machine, wherein

-   -   the direct write machine being provided with a coordinate system        for controlling write operations;    -   the workpiece having a plurality of dies distributed thereon;    -   each die being associated with a predetermined circuit pattern        in the form of original pattern data;        the method comprising the steps of:    -   a. receiving measurement data being associated with the        workpiece and indicating a measured position of each die in        relation to a reference feature of the workpiece;    -   b. detecting the predetermined reference feature of the        workpiece;    -   c. determining the relation between the reference feature of the        workpiece and the coordinate system of the direct write machine;    -   d. transforming the coordinate system of the direct write        machine dependent on the measured position of each die and on        the determined relation between the reference feature of the        workpiece and the coordinate system of the direct write machine        such that the predetermined circuit pattern is fitted to the        dies on the workpiece;    -   e. writing a pattern on the workpiece according to the        predetermined pattern data in the transformed coordinate system        of the direct write machine.        Summarizing Embodiments of the Method

An embodiment of the inventive method for patterning a workpiece, forexample a wafer, having a plurality of dies, comprises: measuring analignment mark on the wafer or a reference die among the plurality ofdies; measuring a position of at least a first of the plurality of dies;preparing pattern data based on the measured alignment mark and positionof at least the first die; re-sampling the pattern data to fit theposition of at least the first die; and writing a pattern on the waferaccording to the re-sampled pattern data.

Another embodiment comprises: defining the measured position of thefirst die in a coordinate system of a writer by transforming theposition of the first die to the coordinate system of the writer.

The method for patterning a wafer having a plurality of dies, the methodcomprises: measuring an alignment mark on the wafer or a reference dieamong the plurality of dies; measuring a position of at least a first ofthe plurality of dies; preparing pattern data based on the measuredalignment mark and position of at least the first die, the pattern dataincluding vector data translated to fit at least the first die;rasterizing the pattern data; and writing a pattern on the waferaccording to the rasterized pattern data.

Embodiments of Apparatus for Patterning a Workpiece

The inventive method is in preferred embodiments applied in a system ofapparatus for patterning a workpiece. FIG. 9B shows schematically ablock diagram of illustrating embodiments of apparatus for patterning aworkpiece in accordance with embodiments of the invention. The systemcomprises apparatus units including at least one computer systemconfigured to realizing any of the the method steps and/or functionsdescribed above inter alia by means of specifically designed computersoftware program code or specifically designed hardware, or acombination thereof A computer program product according to theinvention comprises computer program code portions configured to controla computer system to perform any of the above described steps and/orfunctions of the method.

The apparatus illustrated in FIG. 9B comprises a measurement unit 12that may be a separate measurement unit directly coupled to a writingtool 20 via a computer system 15 for example a laser direct imaging(LDI) computer system 15 and possibly also via a mechanical connection.In one embodiment the LDI computer system 15 receives a measurement filefrom a separated measurement unit by means of an arbitrary data carrier.The writing tool comprises for example a laser direct write machine.

The computer system 15 comprises a data preparation unit 14, atransformation unit and a writing tool control unit, preferably realizedas software, and is communicatively coupled to the writing tool 20. Thedirect write machine of the writing tool is provided with a coordinatesystem for controlling write operations on a workpiece and a mechanismconfigured for detecting a reference feature on the workpiece,preferably by means of imaging technology.

Embodiments of the computer system 15 further comprises a unit fordetermining the relation between at least one reference feature of theworkpiece and the coordinate system of the direct write machine. A datapreparation unit 14 also comprised in the computer system 15 isconfigured to prepare pattern data before and/or after transformation. Atransformation unit 16 is in one embodiment configured to transformingthe measured position of a plurality of dies to a transformed positiondefined in the coordinate system of the direct write machine comprisedin the writing tool 20 dependent on a determined relation between the atleast one reference feature of the workpiece and the coordinate systemof the direct write machine. In one variation the transformation unit 16comprises a re-sampling unit configured to resample the pattern data tofit the dies. In another variation the transformation unit 16 comprisesa rasterizer configured to rasterize the the pattern data.

The data preparation unit 14 is in one embodiment configured topreparing adjusted circuit pattern data for writing on the workpiecedependent on both the original pattern data and the transformedpositions, wherein the adjusted circuit pattern data represents thecircuit pattern of the plurality of dies, or group of dies, such thatthe adjusted circuit pattern is fitted to a plurality of sub-areas ofthe workpiece area, and wherein each sub-area is associated with a die,or group of dies, among the plurality of dies distributed on theworkpiece. The writing tool control unit 18 is configured to control thedirect write machine of the writing tool to writing a pattern on theworkpiece according to the adjusted circuit pattern data. Similarly,different embodiments of the units of the apparatus are configured tocarry out the various embodiments of the method.

In an alternative embodiment of the inventive concept the transformationunit 16 is configured to transform the coordinate system of the writingtool, e.g. a direct write machine, as described above.

Summarizing Embodiments of the Apparatus

An embodiment of the inventive apparatus for patterning a workpiece, forexample a wafer, having a plurality of dies, the workpiece or waferhaving a plurality of dies, the apparatus comprising: at least onemeasurement unit configured to measure an alignment mark for the waferor a reference die among the plurality of dies, and configured tomeasure a position of a first of the plurality of dies; a datapreparation unit configured to prepare pattern data based on themeasured alignment mark and position of the first die; a re-samplingunit configured to resample the pattern data to fit the position of atleast the first die; and a writing tool configured to write a pattern onthe wafer according to the re-sampled pattern data.

In one embodiment of the apparatus, the measurement unit is furtherconfigured to define the measured position of the first die in acoordinate system of a writer by transforming the position of the firstdie to the coordinate system of the writer.

In another embodiment, an apparatus for patterning a workpiece, forexample a wafer, having a plurality of dies, the apparatus comprises: ameasurement unit configured to measure an alignment mark on the wafer ora reference die among the plurality of dies, and configured to measure aposition of at least a first of the plurality of dies; a datapreparation unit configured to prepare pattern data based on themeasured alignment mark and position of at least the first die, thepattern data including vector data translated to fit at least the firstdie; a rasterizer configured to rasterize the pattern data; and awriting tool configured to write a pattern on the wafer according to therasterized pattern data.

In a further embodiment, the measurement unit is configured to definethe measured position of the first die in a coordinate system of awriter by transforming the position of the first die to the coordinatesystem of the writer.

Alignment Between a Plurality of Layers

In a development of the inventive concept, a pattern within a firstlayer is aligned to certain features in another, preceding or subsequentlayer. This is applied in the manufacturing of a multilayer stack ofintegrated components, i.e. dies in this context, for example a 3DSystem in Package SiP. According to the invention this is typicallyachieved by providing a first pattern for a re-routing layer which isaligned and fitted to dies distributed on the first layer of the workpiece, and at the same time is fitted to a different second pattern withdies that are to be connected. Possibly, the second pattern is locatedon a second work piece that is to be connected to the first work piece.

FIG. 9C illustrates an example of a 3D SiP. In the example of FIG. 9C,the pieces 1110 represent a first type of dies in the form of activecomponents, whereas the pieces 1108 represent a second type of dies inthe form of passive components. The components are connected to the edgeof the workpiece 1112 or to each other by a process such as alithography process.

When dies for example in the form of active and/or passive componentsare stacked on each other in and/or on a work piece, and/or on separateworkpieces that are to be connected, or placed on opposite sides of theworkpiece (e.g., as in FIG. 11A-B), one or several parts of the patternmay have a transformation connected to the workpiece where the machineprints and where one or several parts of the pattern have atransformation that is connected to the die (currently known as 2D- or3D-embedded dies, fan-out dies, double sided fan-out dies, etc.) thatcomprise the layer(s) on top on this layer.

The purpose of the process is to connect conductive material to thedies/components such that the dies/components are connected to the edgeof the workpiece or to each other by a process (e.g., a lithographyprocess). It is relatively important for the quality of the electroniccontact that the conductive material connects accurately to thedie/component connections.

An LDI may use several different pattern transformations to achievesufficiently accurate connections. When stacking 3D dies/components,different transformations on different parts of the patterns maysuppress and/or prevent tight placement restrictions when placing thecomponents on subsequent layers. Instead, a process similar to a2D-fan-out or embedded dies combined with pattern transformation may beused for all or substantially layers with relaxed requirements on thedie/component registration (placement) for each layer.

FIG. 10A is a top view and 10B is a side view of a workpiece 1204, andillustrate an example of how one part 1202 of a pattern is connected tothe dies 1206,1208 on a layer of a workpiece 1204. In FIG. 10B, only onelayer of pattern 1202 is shown. However, several pattern layers may beadded with same or individual transformation.

FIG. 11A is a top view and FIG. 11B is a side view of a multilayerstack, here a system in package stack, and illustrates an example of howa first workpiece 1204 as in FIG. 10 is overlayed with a second workpiece 1302 having dies, in this case of a different type distributedthereon.

In FIGS. 11B and 11B, only one layer of a pattern 1202 is shown.However, several pattern layers may be added with the same or individualtransformations. Also, only two layers of dies (components) are shown inthis example. However, more layers of dies may be added. Also, the diesor other components may be placed inside and/or on the edge of theworkpiece. As described above, the transformation for subsequent layersmay be based on measurement data. The measurement data may be obtainedin the writer or in an external measurement machine. The transformationused for the next layer may not be derived from the previous layerbecause a specific component may have a connection to other dies,components or PCB/substrate/workpiece or other connectors on higherlayers (different layers). Moreover, if a stack includes severalworkpieces (e.g., carrier wafers), patterning steps may be performed totake care of transformations of surrounding dies, for examplewafers/components/PCB/substrate) or parts of surrounding dies on all orsubstantially all layers connecting the workpieces in the stack. Part ofthe transformations on both sides may also be taken into account to addup to a total overlay.

Thus, typically a first pattern in a first layer is aligned to dies, orgroups of dies, and is at the same time aligned to a second pattern forconnection points that are associated with a preceding or subsequentlayer. The second pattern is usually a subset of the first pattern,where a part or a portion of the pattern is marked or detected to be setin contact with another layer or pattern. This marking may for examplebe realized by means of labels in the pattern data file, or be detectedautomatically by a suitable algorithm.

The alignment of the first pattern to the dies, or group of dies, ispreferably carried out as described above. When applying thisdevelopment of the inventive concept, there is one or a plurality ofconnection points in the pattern of a currently written layer. Theconnection point in a pattern may be a line or a point with a dimensiondelimited for example by the surface layer material or the size ofprintable features. The connection point may also have a comparativelylarger area and have the characteristic of a contact pad. The connectionpoints or the contact pads are intended to be connected to connectionpoints of dies.

The inventive concept is in different embodiments applied as method, asystem of apparatus and/or a computer program product configured forpatterning a layer of a workpiece in a direct write machine in themanufacturing of a multilayer stack. The direct write machine istypically provided with a coordinate system for controlling writeoperations on a first layer of a first workpiece typically having aplurality of dies distributed thereon. Typically, each of the pluralityof dies have a plurality of connection points.

Typically, each die is associated with a first circuit pattern for arerouting layer. The circuit pattern of the rerouting layer comprisesfirst pattern portions that shall fit to the connection points of thedies and second pattern portions that shall fit to specific features inat least one other preceding or succeeding second layer. The specificfeatures in the second layer may for example be portions of a secondpattern or connection points of dies in the other layer, contact points,contact pads, vias, contacts, lines or other features to which a patternmay be fitted. Further, the second layer may be in the same or in adifferent work piece that will be connected to the first workpiece. Thesecond layer has for example been previously formed in a preceding layeror is to be subsequently formed in a succeeding layer on the first orsecond workpiece. It is thus understood that there may be intermediatelayers between the first and the second layers. In the case when a firstand a second workpiece are connected or adjoined this usually takesplace later in a subsequent assembling step and with appropriatealignment between the patterns of the different workpieces. Put in adifferent wording for some embodiments, the second layer(s) has beenpreviously formed or is to be subsequently formed on the same firstworkpiece or on/for a second workpiece that is to be joined to the firstworkpiece in the stack.

The first circuit pattern are in different embodiments represented inthe form of original circuit pattern data and/or transformed circuitpattern data adjusted to fit the connection points on the die(s). Suchtransformed circuit pattern data is preferably adjusted by means of theabove described method.

Embodiment of the method, which is schematically shown in FIG. 11C,comprises a selection of the following steps:

-   1402: Retrieving first circuit pattern data of a first circuit    pattern representing at least one first sub-area of said first layer    of the first workpiece.-   1404: Retrieving second circuit pattern data of a second circuit    pattern representing at least a second sub-area associated with a    plurality of connection points of one or a plurality of specific    features of a second layer(s).-   1406: Determining required first fitting tolerance(s) for adjusting    the first circuit pattern at least to the first sub-area of the    first layer.-   1408: Determining required second fitting tolerance(s) for adjusting    the first circuit pattern so that the connection points of the    adjusted first circuit pattern fit to the connection points of at    least one second circuit pattern.-   1410: Preparing adjusted first circuit pattern data that fit the    adjusted first circuit pattern.-   1412: Writing a pattern on the first workpiece according to the    adjusted first circuit pattern data.

Details and embodiments of these steps are further explained below.

-   1402: Retrieving first circuit pattern data of a first circuit    pattern representing at least one first sub-area Of said first layer    of the first workpiece, wherein the at least one first sub-area is    associated with, and is covering, at least one die of the plurality    of dies of the first layer.-   1404: Retrieving second circuit pattern data of a second circuit    pattern representing at least a second sub-area associated with a    plurality of connection points of one or a plurality of specific    features of a second layer(s), wherein the second layer(s) is one or    a plurality of preceding or succeeding layer(s) of the first    workpiece and/or one or a plurality of layer(s) in a second    workpiece that is to be connected to the first workpiece, and    wherein at least one of the plurality of connection points of the at    least one die of the first layer is adapted for connecting to at    least one of the connection points of the one or plurality of    specific features of the second layer(s).

In different embodiments, at least some of the specific features of thesecond layer(s) represent contact points in form of, or associated with,one of pads, vias, contacts, lines or dies.

As mentioned, the second layer may have been previously formed on asurface of the workpiece, or may be subsequently formed in the same orin a different workpiece.

The first circuit pattern data and/or the second circuit pattern datamay for example be received or retrieved from original pattern data,from measurement data produced by a measurement stage or from adjustedpattern data generated in a previous alignment procedure, such as thatdescribed above. So, in one embodiment the retrieving of first circuitdata of the first circuit pattern comprises the steps of:

-   a. receiving measurement data being associated with the first    workpiece and indicating a measured position of a plurality of the    dies, or group of dies, distributed on the first workpiece in    relation to at least one reference feature of the workpiece;-   b. detecting the at least one reference feature of the workpiece;-   c. determining the relation between the at least one reference    feature of the first workpiece and the coordinate system of the    direct write machine.-   1406: Determining required first fitting tolerance(s) for adjusting    the first circuit pattern at least to the first sub-area of the    first layer.-   1408: Determining required second fitting tolerance(s) for adjusting    the first circuit pattern so that the connection points of the    adjusted first circuit pattern fit to the connection points of at    least one second circuit pattern representing the one or plurality    of dies of the second layer(s).-   1410: Preparing adjusted first circuit pattern data that fit the    adjusted first circuit pattern to:

i. the at least one first sub-area of the first layer within therequired first fitting tolerances; and

ii. the at least one of the connection points of the at least one die ofthe first circuit pattern representing the at least one first sub-areato the at least one of the connection points of the one or plurality ofdies of the at least one second circuit pattern within the secondfitting tolerance(s).

The adjusted first circuit pattern data is preferably prepared bytransforming connection point patterns of the first pattern data toadjusted connection point patterns having positions and surface areascovering the required second fitting tolerance(s). The position of anadjusted connection point pattern is the nominal position of theconnection point pattern in the original circuit pattern data of thefirst circuit pattern.

One embodiment is configured to make the adjusted connection pointpatterns each have a position and surface area within which all pointshave a distance less than the required fitting tolerance(s) from theideal position.

In one embodiment the preparing of the adjusted first circuit patterndata comprises:

-   a. rendering the first circuit pattern data from a set of ideal    pattern data; then-   b. re-sampling the first circuit pattern data in order to fit the    adjusted first circuit pattern to    -   i. the at least one first sub-area of the first layer within the        required first fitting tolerances; and    -   ii. the at least one of the connection points of the at least        one die of the first circuit pattern representing the at least        one first sub-area to the at least one of the connection points        of the one or plurality of dies of the at least one second        circuit pattern within the second fitting tolerance(s).

Another embodiment, the preparing of the adjusted first circuit patterndata comprises re-sampling the first circuit pattern data in order tofit the adjusted first circuit pattern data to the at least one firstsub-area of the first layer, wherein the first circuit pattern data isre-sampled independently of the re-sampling of the at least one secondcircuit pattern data; and merging the re-sampled first circuit patterndata with the at least one re-sampled second circuit pattern data inorder to produce a re-sampled third circuit pattern data representingboth the adjusted first circuit pattern and an adjusted at least onesecond circuit pattern within the first and the second fittingtolerances. This is further explained below in connection with anembodiment employing merging of data collections.

A further embodiment comprises transforming the measured position of theplurality of dies, or group of dies, distributed on the workpiece to atransformed position defined in the coordinate system of the directwrite machine dependent on the determined relation between the at leastone reference feature of the workpiece and the coordinate system of thedirect write machine; preparaing the adjusted first circuit pattern datafor writing on the workpiece dependent on the original pattern data andthe transformed positions, wherein the adjusted first circuit patterndata represents the circuit pattern of the plurality of dies on thefirst workpiece, such that the adjusted first circuit pattern is fittedto a plurality of sub-areas of the first workpiece area, and whereineach sub-area is associated with a die, or group of dies, among theplurality of dies distributed on the workpiece.

The preparing of the adjusted first circuit pattern data may alsocomprise rendering the first circuit pattern data from a set of idealpattern data; then re-sampling the first circuit pattern data dependenton the measured position data of the at least one die(s) and on thetransformed position and shape of the first workpiece in order to fitdata to each die on the first workpiece in the coordinate system of thedirect write machine;

or re-sampling the first pattern data dependent on measured positiondata of a group or a cluster of the plurality of dies and on thetransformed position and shape of the workpiece in order to fit datarepresenting the associated with the plurality of on the first workpiecein the coordinate system of the direct write machine.

So, for example, as shown in FIG. 11B, the connection point pattern 1202is transformed such that a connection point 1310 of a die 1206 in afirst layer 1204 and a connection point 1312 of a die 1306 in a secondlayer falls within the area of the connection point pattern 1202, andthereby both connection points 1310,1312 are able to make electriccontact via the connection point pattern 1202.

-   1412: Writing a pattern on the first workpiece according to the    adjusted first circuit pattern data.

The steps above may further comprise the step of first determiningrequired fitting tolerances for adjusted connection points to fit to theconnection points of the dies in the first circuit pattern.

These steps may comprise steps as described above for the part of theinventive concept operating to align circuit pattern data to dies on aworkpiece.

Adjustment of Connection Points and Required Fitting Tolerances

The position of connection points, for example pads or conductor lines,that are to be aligned downwards with previous layers or upwards withsubsequent layers is in one embodiment provided in the form of ameasurement data file. Preferably, the manufacturer, i.e. the operatorof the direct write machine, specifies a tolerance or a set oftolerances that should be achieved between the written points, pads orlines and their respective ideal position before or after atransformation. The ideal positions are given in the ideal pattern datafrom the design of the pattern. The position and/or fitting of theresulting written pattern is, in one embodiment, measured after or inconnection to writing and the achieved fitting is compared to therequired fitting tolerance. If the achieved fitting is outside therequired fitting tolerances, the machine is for example controlled toprovide a warning signal or stop writing operations.

The thresholds for required fitting tolerances are preferably dependenton the specific layer or type of layer, or specific product or type ofproduct that is manufactured. The required fitting tolerance fordifferent types of layers and products may for example be between lessthan (<) 50 μm (micrometers) and less than (<) 1 μm (micrometer) fromthe ideal position. In one example of a use case the required fittingtolerance is in the range of less than (<) 5-8 μm (micrometers).

The adjusted connection point pattern and the required fittingtolerances are in different embodiments determined in a variety ofmanners. In one embodiment the position of an adjusted connection pointpattern is the nominal position of the connection point pattern in theoriginal circuit pattern data of the first circuit pattern. In oneembodiment, the required fitting tolerance is determined as a positionand/or a surface area covering a projection of the connection point ofthe first circuit pattern and a projection of the connection point ofthe second circuit pattern when the patterns are aligned. In anotherembodiment, the required fitting tolerance is determined by transformingsaid patterns and said layers to a common plane, and calculating therequired fitting tolerance based on distances between ideal pattern dataand adjusted pattern data in said common plane.

The adjusted connection point patterns may each have a position andsurface area within which all points have a distance less than therequired fitting tolerance from the ideal position. Fitting tolerancesare often defined as a distance that is described by the Euclidian normin an arbitrary dimension, usually in 2D (x,y). In embodiments fordifferent applications, the required fitting tolerance(s) is a distanceof less than 50 μm from the ideal position; or a distance less than 1 μmfrom the ideal position; or a distance less than than 5-8 μm from theideal position.

This development of the inventive concept for providing alignmentbetween a plurality of layers is readily combined with the alignment ofpattern to dies within a single layer as described above. The method forproviding alignment between a plurality of layers is in embodimentssimilarly realized as a system of apparatus and/or a computer programproduct.

Embodiment Employing Merging of Data Collections Representing Pattern

In one embodiment, the preparing of adjusted circuit pattern datacomprises storing pattern data for different transformation zones,possibly including stretch zones as explained below, from differentlayers in separate data collections, rasterizing and transforming saiddata collections separately, then merging said separate data collectionsinto a single data collection.

As described above in one embodiment, the preparing of adjusted firstcircuit pattern data comprises re-sampling a first circuit pattern data.The first circuit pattern data is re-sampled independently of there-sampling of a second circuit pattern data. Then the re-sampled firstcircuit pattern data is merged with the re-sampled second circuitpattern data in order to produce a re-sampled third circuit pattern datarepresenting both the adjusted first circuit pattern and an adjustedsecond circuit pattern.

In an example of a practical implementation, pattern data in the form ofpixel maps are merged and resampled. This may include having a userdefining different parts or portions of the pattern in a data file (datacollection), for example pertaining to different layers, and thenrendering every portion e.g. corresponding to every layer with its owndistortion map.

A merging and resampling component receives standard pattern data andcustom pattern data on two data paths. The data paths may be physicallyseparate or interleaved, as on a single data bus or memory accesschannel. By “data path,” we mean to refer to how data is delivered tothe resampling and merging component. The data may come from vector orraster data and may be stored on rotating or non-rotating memory.

For manufacturing, design data, typically a vector data set, isconverted into a common vector format. Vector domain geometry processingis applied in this format. The vector format is then rendered into ageometrical pixel map, producing what we refer to as “standard patterndata”. Pixel domain image processing is applied and the data isresampled into a modulator dependent format for printing.

There are other cases in which edges of a die require different patternsthan the main field of the die. For these purposes, a second pixel mapof custom pattern data can be used. We disclose merging and resamplingthe standard pattern data with the custom pattern data, for instance atthe time when the data is being used to form latent images.

The merging can be performed at various times, before or afterresampling. Resampling in this context means resampling in order to fita pattern to underlying patterns (not to confuse with resampling fordifferent zones as in other embodiments described in this text). Thus,first every file with its transformation is resampled, and thereafter itis in this embodiment optional to merge the bitmap files to a singlefile before or after resampling is carried out fit the pattern of anunderlying layer when the alignment marks have been measured.Accordingly, merging and resampling are represented by a singlecomponent and may be claimed as a single action, because the order ofmerging and resampling depends on the nature of the standard and custompattern data. In some use cases, the merging can be done beforeresampling, allowing the processing to be performed off-line, where timeis less critical. Then, on-line processing is more nearly time-wisedeterministic, allowing optimization of compute power. The resamplingoperation transforms one input map into one output map, which simplifiesthe resampling operation. The combined pixel maps can be accessed forinspection prior to printing.

When merging is performed during resampling, the custom pattern datapixel maps can be generated immediately before printing, immediatelybefore the modulator pixel map is generated. One example of recentcustom pattern data is generated near the time of production with theexact production time to be merged into the pattern.

When merging is performed after resampling, the additional pixel mapsmay also be merged into an existing modulator pixel map. This can bebeneficial when the data flow is partitioned in a way that requires amerge of multiple modulator pixel maps prior to printing.

During merging, the custom pattern data can be tested to determinewhether any customization is required in a particular area, frame ortile. If there is no customization, the merge can be optimized, whetherby bypassing the merge altogether or performing a merge that will notchange the pixel values in the standard pattern data.

The merge between the standard pattern data in the base geometricalpixel map and the custom pattern data in additional geometrical pixelmap(s) can be performed for matching or much different pixel grids.First, identical and aligned pixel grids can be merged. In the simplestform, the merge is performed on multiple pixel maps where the grids andtiles are matching, i.e., the pixel dimensions and the alignment of themaps are identical. In this case, the merged can be performed beforeresampling, pixel-to-pixel, with a simple merge operation. Alternativemerge operations are described below.

Second, identical but offset pixel grids can be merged. Here, the gridsof the multiple pixel maps have the same pixel dimensions, but areoffset so that a single pixel in one map does not correspond to a singlepixel in the other map. In this case, the offset can be removed bysnapping the offset of the additional maps to match the base map. Thenthe merge is performed before resampling, pixel-to-pixel, with a simplemerge operation. Or, multiple adjoining pixels in the additional map canbe resampled to decide the value of the resulting pixel to be merged.

Third, non-matching pixel grids can be merged. An example comprisesgrids of different pixel size and tile size. The standard pattern datais in a first grid and the custom pattern data is in a second grid.Three pixels of custom data fit over twelve pixels of standard data. Aconnecting pattern overlays pads of an open gap. This is asimplification of programming a custom pattern of ones and zeros asclosed and open connections. When the pixel grids are not matching,either by pitch or offset, the merge can be performed by resampling theimages to a common grid and tile. Or, multiple grids could be resampledat the same time and the resampling results merged.

When pixel grids match, the merge can be done pixel-by-pixel with asimple one-to-one merge operation. Depending on the data involved,different merge operations can be used, such as Replace, Add, Subtract,XOR, AND, OR. The operations Replace, Add and Subtract can be used forpixels are represented by floating point or integer values, but thelogical operations are difficult to apply to floating point values, dueto exponent scaling. If the pixels are represented by integer values,any of these merge operations can be applied.

Workpieces that can benefit from custom pattern data include silicon orsemiconductor wafers, circuit boards, flat-panel displays and substratesof flexible material used in roll-to-roll production. For example acircular wafer and a rectangular substrate on which multiple dies areformed. The dies are separated to form chips or flat panel substrates.

Data for a pixel-based exposure system that prints in a sequentialmanner is “flattened” (all data contributing to one pixel aggregated)and localized. The pattern represented as a rendered geometrical pixelmap (GPM 121) fulfils these properties and makes a suitable format asintermediate storage.

A re-sampling process converts the GPM into modulator pixels in amodulator pixel map (MPM 123). Image processing and morphologicaloperations can also be applied during this re-sampling process. It ispossible to apply the image processing and morphological operations atboth local parts of the pattern, such as over the exposure system fieldof view, or globally over the pattern. The image processing andmorphological operations include, but are not limited to, scaling,translation, rotation, distortion and sizing. These operations can beused to compensate both for how the exposure system projects pixels ontothe mask/substrate and for properties of the mask/substrate.

Due to fidelity requirements and the potential information loss duringthe re-sampling process, the intermediate pixel map (GPM 121) has ahigher resolution than the Modulator Pixel Map (MPM 123). By usinggradient information in the re-sampling process, the memory resolutionrequired to satisfy the requirement of the GPM 121 can be significantlyreduced.

The majority of the pattern dependent processing steps are done duringgeneration of the GPM 121. The re-sampling is primarily used to handlelocalized pattern dependent (morphological) operations. It isadvantageous to limit re-sampling to localized pattern dependentoperations, as this improves the predictability of computational effortfor the re-sampling. Predictable computational effort, in turn, makes iteasier to optimize the configuration.

The technology disclosed includes a method of forming a custom latentimage in a photosensitive layer over a substrate. This method includesreceiving standard data on a first data path and receiving custompattern data on a second data path. We intend for data paths to bebroadly construed. Standard pattern data is pattern data that isrepeatedly used for multiple dies or areas within a die and for multiplesubstrates in a batch, subject to customization. Custom pattern data isused to modify the standard pattern data to produce a custom latentimage. The method further includes resampling and merging the standardcustom pattern data to form a merged-rasterized pattern data thatrepresents the physical, custom latent image to be formed in a radiationsensitive layer. A latent image may be positive or negative, dependingon the resist or other radiation sensitive material applied over thesubstrate. In typical device manufacturing processes, a latent image isdeveloped and parts of the radiation sensitive layer removed to form apattern. The pattern is used to add or remove material as part offorming electronic devices.

Pattern Reconnection after Individual or Multipart Alignment

A further development of the inventive concept deals with the problemaspect of achieving reconnection or healing of pattern portions thatcomprises connection lines between dies after an alignment. Embodimentsof this part of the invention are devised to recalculate the pattern inorder to enable two or more arbitrarily placed dies to beinterconnected. These embodiments are applicable in combination with theabove described embodiments for interconnecting dies in the same layer,or to adjust connection points in a first pattern portions of a firstlayer to fit to second pattern portions associated with features,references or dies in a second layer. This development adjusts a patternto fit first connections points (or connection pads) associated with afirst die to second connection points (or connection pads) for exampleof a second die or a second pattern.

This further development of the inventive concept is based on apartition of areas on a work piece into first areas and second areas (orfirst and second sub-areas) with different requirements on alignmentbackwards in relation to preceding layers. The first areas are herecalled sacred zones and need to be well aligned to layers beneath acurrently processed or patterned second layer. The second areas are herecalled sacred zone and are less sensitive with regard to alignment topreceding layers beneath the current layer or to subsequent layers abovethe current layer.

Embodiments of this further development is applied as a method, a systemof apparatus and a computer program product configured for patterning asecond layer of a work piece in a direct write machine in themanufacturing of a single or multilayer system-in-package stack. Thework piece typically has a first layer with a plurality of electricalcomponents that are arbitrarily or randomly placed on the work piece.Dies are as mentioned above in this text the expression use for any typeof component associated with electronics. Typically, each die hasconnection points where some of them need to be connected between thedifferent dies. A first pattern wherein different zones or sub-areascomprising connection points of dies distributed in the first layer areassociated with different requirements on alignment.

Sacred zones and stretch zones are detected in the first pattern. Thenthe first pattern is transformed such that connection points in adjacentsacred zones are aligned within a predefined and/or presettablealignment deviation parameter. Further, in the transformation,deviations between the positions of corresponding connection points inthe sacred zones are compensated for in the patter for connection pointsof stretch zones. Adjusted pattern data is calculated to realize thetransformation and a pattern is written on the layer of the work pieceaccording the adjusted circuit pattern data.

Different embodiments include a method for reconnection of a patternincluding a plurality of sacred zones and a plurality of stretch zonescorresponding to the sacred zones on a first layer, the methodcomprising: connecting boundaries of adjacent ones of the sacred zonesafter individual transformation of the pattern; and compensating, in thestretch zones, for the difference or offset between connection pointsbetween the adjacent sacred zones. For example, the compensation islinear. The method may further include providing an additional zone forconnection between the first layer and at least one additional layer.

The invention further comprises embodiments of a method for reconnectionof a pattern on a workpiece having first, second and third layers formedsequentially on one another, the method comprising: transforming apattern file for the second layer such that connection points in thefirst layer are connected to connection points in the third layer. Theconnection points are in different embodiments vias.

In a fan out or similar process (e.g., embedded, etc.), many dies and/orpassive components (of one or several types) are placed for example on acarrier wafer or any other applicable workpiece. After the dies havebeen placed on the carrier wafer, one or more patterning steps areperformed on one or more layers of the workpiece. Each die or any otheractive or passive component has its own unique transformation (e.g.,rotation, translation, etc). If the pattern is aligned to eachdie/component using an LDI machine, differences in individualtransformations may create edge roughness, or bad connections for linesthat should connect the dies with each other or other layers (e.g.,substrate/3D SiP/PCB/workpiece). Accordingly, it may not be possible (orunsuitable) to individually align to each component. As explained in thebackground section above, FIG. 16A illustrates an example of thisproblem. More specifically, FIG. 16A illustrates an example after apattern has been adjusted to the transformation of each chip.

In accordance with the invention, sensitive regions such as chip areasthat need to be relatively well aligned to layers beneath are eithermarked as sacred regions in the pattern file, i.e. in circuit patterndata, or a well defined algorithm in the machine identifies and locatesthese regions in the circuit pattern data (e.g., find all orsubstantially all regions with pads that should connect to vias on thelayer beneath). Regions that are not very sensitive with regard toalignment to layers beneath and/or subsequent layers are used as stretchzones as shown in FIG. 14, which is an illustration of identified sacredregions or sub-areas of the workpiece 1702 and 1704 of two dies locatedwithin or associated with these sub-areas, and identified stretchregions or sub-areas 1706. In this example the stretch regions areillustrated to be continuously linked, but of course stretch regions maybe isolated from each other as well. The terms sacred zone, sacredregion, sacred sub-area, and similarly stretch zone, stretch region,stretch sub-area, respectively, are used as alternative expressions.

In a sacred zone, the alignment transformation of the pattern shouldpreferably be best possible or as close to best possible given thetransformation of the underlying pattern (or die, component, etc). Onesolution employed in some embodiments is to connect the boundaries ofthe sacred zones in the orthogonal coordinate system (and/or in the CADsystem) after individual transformation. The difference between thesepoints after the individual alignment is compensated for in the stretchzone. The compensation in this region may be linear as is shown in thefigures discussed in more detail further below.

FIG. 15 illustrates example patterns in the design (CAD) domainassociated with dies 1502, 1504. In FIG. 15, the shown area of aworkpiece is identified or marked as an allowed stretch zone within theintermittently lined sub-area 1510 and the rest of the pattern is asacred zone.

FIG. 16A illustrates a pattern associated with dies 1502,1504 resultingfrom a patterning without using the stretch zone concept of theinvention, and in which patterning only individual transformation isapplied to the pattern. Some of the connection points 1508 are notconnected. FIG. 16B illustrates an example pattern associated with dies1502,1504 where the stretch zone concept is used to reconnect regionsthat were connected in the ideal (original) coordinate system using alinear connection between the sacred zones. The connection points 1508are all connected in the stretch zone 1510. The transformation in thestretch zones that connect the sacred zones may also be of other types,for example, a linear combination between the individual transformationsor an approximation of these using splines or other fitting methods, forexample as described in connection with the previous developments andembodiments of the inventive concept.

FIGS. 17A and 17B are illustrations of example patterns associated withdies 1502,1504 where a linear combination between the individualtransformations with the boundary condition that the transformation iscorrect at the boundaries of the sacred zones. More specifically, FIG.17A illustrates an example pattern without using the stretch zoneconcept and in which only individual transformations are applied to thepattern. In the example, it is shown that connection points 1508 are notconnected. FIG. 17B illustrates an example pattern if the stretch zoneis used for the sub-area 1510 to reconnect regions that were connectedin the ideal (original) coordinate system using a linear combinationbetween the individual transformations.

An expansion of this example embodiment is to also introduce a third“pattern area type” having the same transformation in order to makeseveral individual transformations to fit to one transformation in thenext layer or some layer in-between. FIG. 18 illustrates an example inwhich an additional zone 2102 has been identified or marked eitherautomatically by the machine or in the pattern data file. The third zonetype sub-area 2102 in FIG. 18 is for example intended to be connected tothe next layer or to an external component, PCB, etc.

FIG. 19A illustrates an example in which a stretch zone 1510 is used butwhere a third zone is not applied. FIG. 19B illustrates an example inwhich a third zone 2102 is applied. As seen in FIGS. 19A and 19B,pattern portions that are associated with dies 1502, 1504 of theworkpiece, (for example a chip area), has its transformation. Thestretch zone 1510 with the patterns that connect the dies 1502,1504 andthe zone in the third area 2200 has a common transformation. Thetransformation for the third zone 2102 may be chosen arbitrarily (e.g.,one of the sacred transformations, linear combination, etc.) or chosento match a known transformation in the next layer or an externalcomponent, PCB, component in carrier wafer, etc.

Example embodiments should not be limited to 3 types of zones. Rather,any number of zones may be used and rules for the transformations andalso how the zones are connected may be varied. The reconnection betweenthe zones may be done directly in the vector domain or in the rasterizedimage using resampling.

An example embodiment including three layers will now be described. Inthis example, the first layer includes a number of given points. In thisexample, “given” indicates that the positions of the points have beengiven or provided by an alignment system and/or additional measurementdata from external measurement machine, from a pattern file, etc. Thepoints may be via holes (vias), which may be connected to componentslike dies for example in the form of active or passive components, butalso connected to the edge of a workpiece or to another layer in aworkpiece. The workpiece may as exemplified further above be asubstrate, PCB, carrier wafer, panel etc., but is not limited to theseexamples. The position data may be given for each point, for a sectionor group of points of points, for each die or component, for a sectionor group of dies or components, etc.

In this example embodiment, there exists a third layer with the same orsubstantially the same properties as the first layer. For the secondlayer, which is to be created between the first layer and the thirdlayer, there is a pattern file that connects the points in the first andthird layers. However, this is a case where some or all of the points inat least one of the first and third layers may have been misplaced fromtheir original position described in the pattern file. One part of theinnovation is to transform the given pattern file for the second layersuch that the points in first layer and the third layer are connectedand this pattern is printed with a direct write machine on the first orthird layer. In one example, this may be done in the following way:

-   1. Sensitive regions such as points or point areas that need to be    relatively well aligned to one or both of the surrounding layers    (e.g., one or more of the first and third layers) is marked as a    sacred region in the pattern file or a well defined algorithm in the    machine may be used to locate these regions (e.g., find all regions    with pads that should connect to via/vias on the surrounding    layer(s)).-   2. Regions that are not very sensitive to aspect on alignment to the    surrounding layers and/or subsequent layers are used as stretch    zones. In the sacred zone, the alignment transformation of the    pattern may be best possible or close to best possible given the    transformation of the surrounding patterns.-   3. One example solution is to connect the boundaries of the sacred    zones in the orthogonal coordinate system (and/or in the CAD system)    after individual transformation. The difference between these points    after the individual alignment is compensated for in the stretch    zone. 4. The compensation in this region may be linear or another    type, for example, a linear combination between the individual    transformations or an approximation of these using splines or other    fitting methods.

Example embodiments should not be limited to a certain number ofpoints/zones. Rather, an arbitrary number of points/zones are allowed,and the rules for the transformations and how they should be connectedmay be varied. The reconnection between the points/zones may be donedirectly in the vector domain or in the rasterized image usingresampling.

In the example shown in FIG. 20A, two dies for example chips have bothconnections to each other and a common connection to a next layer in aworkpiece (for example PCB/substrate/workpiece). Black dots 2306represent sacred regions for a first die, for example a chip orcomponent on a workpiece 2302, (where the sacred regions for examplecomprises connections to a via. White dots 2308 represent sacred regionsfor a second die. The grey dots 2307 are sacred regions for connectionsto a next, subsequent layer of the workpiece. The regions in-between thedots marked as black lines are stretch zones 2310.

In this example, the first die on the workpiece has a translation ofabout 20 μm in the X-direction and about −20 μm in the Y-direction. Therotation is about −10 mrad. The second die has a translation of about−20 μm in the X-direction and about −20 μm in the Y-direction. Therotation is about 10 mrad. The transformation data may be obtained froma separate measurement performed in or outside the machine or inconnection with the actual writing. The transformation of the grey dots2304 have, in this case, all been set to 0. If no pattern healing orreconnection is performed in the stretch zone, the lines (connectors) donot meet the boundary condition at the edge of all sacred zones.

Broken lines 2305 or connectors may occur in printed patterns withoutcompensation. If example embodiments are applied and the difference orpart of the difference in the transformations in the stretch zone istaken care of, the broken line or connector phenomena may be improvedand even be removed.

Example transformation maps to be used in a compensated pattern areshown in FIG. 21A-B. The transformation maps may be calculated as soonas the relative measurement data of the dies/components are determined.The global workpiece transformation is then a global transformation ofthis map.

FIG. 22A shows an example printed pattern with compensation As seen inFIG. 22A, the sacred zones 2308 has the correct transformations and theconnectors (pattern) 2010 between the sacred zones have been stretchedto support the boundary conditions.

This example approach may alter the length of the connectors by arelatively small amount. It is possible to compensate for thisalteration by performing corrections in pattern data in the vectordomain or by applying a filter in the rasterized domain, for example ifa buffer is provided.

A preferred embodiment of the method, which is schematically shown inthe flow chart of FIG. 22B, comprises the steps of:

-   2252: Detecting sacred zones in first pattern that have a high    requirement on alignment to selected features of the    system-in-package stack or to the placed components.

The sacred zone is in one embodiment detected by a preset marking in theoriginal circuit pattern data, or as in another embodiment detected by arecognition algorithm devised for recognizing a sacred zone in theoriginal circuit pattern data according to predefined rules. An exampleof such a predefined rule is that the occurrence of a certainrecognizable feature, for example a connection point, a via or a contactpad, indicates a sacred zone.

-   2254: Detecting stretch zones of the first pattern that are allowed    to have a lower requirement on alignment to other features of the    system-in-package stack.-   2256: Transforming the first pattern by calculating adjusted first    pattern data comprising transformation of the original circuit    pattern such that:-   i. connection points in adjacent sacred zones are aligned within a    pre-settable alignment deviation parameter; and such that-   ii. deviations between the positions of corresponding connection    points in the sacred zones are compensated for in the pattern for    connection points of the stretch zones.

The transformation for the circuit pattern in the sacred zone is in oneembodiment such that connection points in adjacent sacred zones areconnected also after individual transformation.

-   2258: Then writing a pattern on the layer of the work piece    according to the adjusted pattern data.

A further developed embodiment includes the notion of an additionalthird zone type. Such as development further comprises:

-   a. Detecting an additional zone type of the circuit patterns of the    dies that comprises connection points for connection between a first    layer and at least one second layer;-   b. Calculating adjusted circuit pattern data using a selected    transformation for circuit patterns of the additional zone type.

The same transformation types as for the sacred zones or stretch zonesmay be used for circuit patterns of the additional zone type.

Different transformations may be used, for example any of thetransformations described above for different developments of theinventive concept. For example, the transformation for alignment in thesacred zone is a selection of linear or non-linear transformation.Similarly, the transformation for compensation in the stretch zone is aselection of linear or non-linear transformation.

There are different alternatives for preparing an adjusted circuitpattern. For example, the adjusted circuit pattern is prepared bytransformation of the circuit pattern data in a vector domain or in arasterized image.

The different variations of this development of the inventive conceptmay also be simultaneously matched to a second pattern. Such embodimentsare advantageously combined such that a first circuit pattern data isadjusted to fit connection points or contact pads of a first die (orcomponent) to connection points or contact pads of a second die (orcomponent), and to a second pattern simultaneously. In short, themethods of any of the preceding embodiments, may thus also comprise thatthe first pattern is transformed to an adjusted first pattern data alsoaligning to features of a second pattern in a preceding or succeedinglayer.

Alignment Optimization with Respect to a Plurality of Layers

The above described embodiments are in variants of the inventive conceptfurther developed with optimization of the alignment with respect toseveral layers. These embodiments of the invention solve the problemaspect of minimizing the errors that may occur from layer to layer, andmay be applied on workpiece having or not having embedded dies.

When writing patterns over several layers, the overlay between eachlayer is critical with regard to overall alignment accuracy. Alignmenterrors arise due to limitations in the alignment transforms. FIG. 27illustrates a cross-section view of a workpiece 2702 with a plurality oflayers LN, LN+1, LN+2, LN+3 over embedded dies 2704. Patterns 2712 aregenerated in each layer in this example for the purpose achieving aconnection path between connection points of the dies to solder bumps2710 having a predetermined position on the top layer LN+3. As can beseen in FIG. 27 part A, the pattern portions in the different layersthat make up the intended connection paths are well aligned to eachother. However, some of the intended connection paths (middle and to theright) are not connected to the respective solder bumps 2710.

FIG. 28 illustrates a cross-section view of a workpiece 2702 with aplurality of layers LN, LN+1, LN+2, LN+3 with a predetermined boundarylayer 2802. Patterns 2712 are generated in each layer in this examplefor the purpose achieving a connection path between connection points ofthe predetermined boundary layer 2802 to solder bumps 2710 having apredetermined position on the top layer LN+3. As can be seen in FIG. 28part A, the pattern portions in the different layers that make up theintended connection paths are well aligned to each other. However, someof the intended connection paths (middle and to the right) are notconnected to the respective solder bumps 2710.

In FIG. 23 part A illustrates a pattern placement 2302 (crossed circlesymbol) in a first layer N. Part B illustrates an alignment transform2305 (star symbol) used for layer N+1. In this example, the writemachine for this layer can adapt a non-linear transformation that givesa perfect fit to the measurement points. Part C illustrates an alignmenttransform used for layer N+2 that is written with a write machine thatin this example is limited to using a linear conformal transformation.FIG. 23 part C illustrates a resulting large overlay error which maygive rise to a situation similar to that illustrated in FIG. 27 part Aand FIG. 28 part A. According to the invention the problem is solved bydistributing the error and the compensation of the error between thelayers. Embodiment of the invention provides distribution of alignmenterrors and compensation from a layer N to a layer N+1 and/or from layerN+1 to N+2, and so on. FIG. 27 part B and FIG. 28 part B illustrates howthe error between subsequent layers LN-LN+3 has been compensated for bycompensating a part of the error in each respective layer.

Embodiments of these further developments are typically applied as amethod of patterning a plurality of layers of a work piece in a seriesof writing cycles in one or a plurality of write machines. The writemachine may be different or the same write machine for different layers.Some layer of the work piece may or may not have a plurality of diesdistributed thereon. Each die is associated with an original circuitpattern and is represented by original circuit pattern data. Further,each die is associated with measurement data of alignment features ofthe respective layer. Limitations in the write machines with regard toperforming or implementing transformations are known and are used in themethod to distribute the errors over a plurality of layers.

Distribution of a Predictable Error Between Layers for Writing onMachines with known Limitations

According to the invention, problem aspects pertaining to alignmenterrors and overlay errors is solved by compensating for errors due todifferent transformation capabilities of different machines bydistributing the errors over the plurality of layers. The inventionsolves the problem aspect of minimizing the errors that may occur fromlayer to layer, and may be applied on workpiece having or not havingembedded dies.

The invention is employed in a method, system of apparatus and/or acomputer program product configured for patterning a plurality of layersof a work piece for example in a direct write machine.

In one embodiment of the inventive concept the error is distributed inpatterning steps, hereafter exemplified with patterning of layer N+1subsequent to a layer N. This embodiment is typically applied when awrite machine that writes the subsequent layer N+1 has limitations that,primarily, are not present in the write machine that writes layer N. Anexample of such a machine is one that writes vias for a higher levellayer.

For example, the machine that writes layer N may be able to compensatefor deviations in scale, rotation, translation and/or orthogonal,whereas the machine that writes layer N+1 cannot compensate fororthogonal deviation. In this kind of situation, the solution accordingto the invention is to make a part for example the half or a third ofthe adjustment in layer N in order to minimize the maximum error betweenlayer N and N+1.

The applied transformation preferably uses a priori information aboutthe limitations of the machine that is intended to write layer N+2.

An example method according to this embodiment comprises the steps of:

-   2802: Calculating a first transformation for alignment of a first    pattern for a first layer based on measurement data for the first    layer and on transformation limitations of a first machine    configured to write the first layer.-   2804: Calculating a second transformation for alignment of a second    pattern for a subsequent layer based on a transformation type to be    used for a machine configured to write the second layer.-   2806: Calculating first and second compensated transformations    distributing the correction of an error in relation to the original    circuit pattern among the first and second compensated    transformations.

In one embodiment, the distribution of the error comprises minimizing,in a parameter space of measurement data for the first layer, a totalstandard deviation for at least the first and second transformations inthe radial domain. In another embodiment, the distribution of the errorcomprises minimizing, in a parameter space of measurement data for thefirst layer, a maximum standard deviation for at least the first andsecond transformations. Further, the distribution of the error maycomprise minimizing, in a parameter space of measurement data for thefirst layer, a maximum standard deviation for at least the first andsecond transformations. In another variety, the distribution of theerror comprises minimizing; in a parameter space of measurement data forthe first layer, a maximum error for at least the first and secondtransformations.

-   2808: Writing pattern on the first and second layers according to    the respective first and second compensated transformations.    Example of Optimizing Transformation

In one example, the transformation is optimized as follows.

Firstly, calculate a transformation Al of layer N+1 with atransformation available on the machine that is intended to write thatlayer. The measurement data for the measured points that the firsttransformation A1 is based upon is denoted B, and the transformationthat describes these points is denoted A.

Secondly, calculate transformation A2 of A1 in points B using thetransformation type that is intended to be used on the machine that willwrite layer N+2.

Then, solve the equation:

$\min\left( {\prod\limits_{B}{{{std}\left( {{{A - {A\; 1}}} + {{{A\; 2} - {A\; 1}}}} \right)}\mspace{14mu}{Or}{\min\left( {\prod\limits_{B}{{\max\left( {{{std}\left( {A - {A\; 1}} \right)},{{std}\left( {{A\; 2} - {A\; 1}} \right)}} \right)}\mspace{14mu}{Or}{\min\left( {\prod\limits_{B}{\max\left( {{\max\left( {{A - {A\; 1}}} \right)},{\max\left( {{{A\; 2} - {A\; 1}}} \right)}} \right)}} \right.}}} \right.}}} \right.$

The equations used to solve for A1 and A2 are only examples. The firstequation minimizes the total standard deviation in the radial domain.The second equation minimizes the max standard deviation for the layers.The third equation minimizes the max error for the two layers. It shallbe noted that the space B may be expanded to more points than themeasured one using interpolation and/or extrapolation of the measurementpoints. It is within the scope to make any compensation of thetransformation A1 using a priori information about the transformationthat should be used in the N+2 layer. These transformations may belinear combinations of transformations A1 and A2 or other kinds ofinterpolations between the transformations. The transformations may alsobe based directly on the points B.

Further Embodiments for Distribution of a Predictable Error

Embodiments for distribution of a predictable error comprises thefollowing variations.

A method of patterning a plurality of layers of a work piece in a seriesof writing cycles in one or a plurality of write machines, applied whenwriting a first pattern on a first layer N of the workpiece, wherein aboundary condition for the available accuracy in fitting a secondpattern for a subsequent layer N+1 to the first layer is determined, forexample fitting to alignment marks or fiducials; the method comprisingthe steps of:

-   Receiving a priori information about the limitation in performing a    limited transformation of the second pattern for said subsequent    layer N+1;-   Calculating: a best fit transformation of the first pattern for the    first layer N that renders a best fit to a preceding layer N−1 using    alignment transformation available for writing on the first layer N,    and the deviation from a perfect fit of the best fit transformation;-   Calculating: a limited transformation applied in transforming the    second pattern for the second layer N+1 to fit the orientation to    said preceding layer N−1, and the deviation from a perfect fit of    the limited transformation;-   Calculating the difference in the deviation between said best fit    transformation and said limited transformation;-   Calculating a compensation of the best fit transformation by adding    a selectable part of said difference in deviations;-   Calculating an adjusted first pattern comprising said compensation;-   Verifying that said adjusted first pattern is within alignment    tolerances for the first layer N:-   Writing, if positively verified, said adjusted first pattern on said    first layer N.

Further optionally comprising a selection of embodiments:

wherein a number N of layers are to be patterned, N being an integer >1.

wherein the step of calculating the transformations is performed in analignment procedure.

wherein the limitation in performing the limited transformation isestimated.

wherein the selectable part of the difference in deviation is selectedas:

-   -   the whole difference in deviation, for example when a high level        of accuracy in alignment is required.

wherein the selectable part of the difference in deviation is selectedsuch that the difference in deviation is distributed locally betweensubsets of layers, for example such that the difference in deviation fora first subset of pattern is compensated for in layer N and thedifference in deviation for a second subset of the pattern iscompensated for in layer N+1.

wherein: a plurality of data collections each representing an individualpattern transformation is separately resampled and stored in a bitmapformat; resampling the data collection(s) to fit the pattern of a layerin the step of calculating an adjusted pattern; optionally merging aselection of the data collections into a single data collection, beforeor after step b.

wherein the distribution of the difference in deviations comprises:minimizing, in a parameter space of measurement data for the first layerN, a total standard deviation for at least the best fit transformationand the limited transformation in the radial domain or using Euclidiannorm.

wherein the distribution of the error comprises:

minimizing, in a parameter space of measurement data for the first layerN, a maximum standard deviation for at least the best fit transformationand the limited transformation.

wherein the distribution of the error comprises:

minimizing, in a parameter space of measurement data for the firstlayer, a maximum error for at least the best fit transformation and thelimited transformation.

wherein the boundary condition may be that:

-   -   a different write machine will write the subsequent layer N+1,        for example a via machine; or that    -   the subsequent layer N+1 is layer for which only a specific type        of transformation may be used, for example a solder layer.        wherein:    -   at least one layer of the work piece has a plurality of dies        distributed thereon;    -   each die being associated with an original circuit pattern and        being represented by original circuit pattern data;    -   each die being associated with measurement data of alignment        features of the respective layer.        further comprising the step of minimizing the errors that may        occur from layer to layer, optionally applied on a workpiece        having or not having embedded dies.

Further an embodiment of a method of patterning a plurality of layers ofa work piece in a series of writing cycles in one or a plurality ofwrite machines,

-   -   at least one layer of the work piece having a plurality of dies        distributed thereon;    -   each die being associated with an original circuit pattern and        being represented by original circuit pattern data;    -   each die being associated with measurement data of alignment        features of the respective layer;        the method comprising the steps of:    -   at least one layer of the work piece having a plurality of dies        distributed thereon;    -   each die being associated with an original circuit pattern and        being represented by original circuit pattern data;    -   each die being associated with measurement data of alignment        features of the respective layer;        the method comprising the steps of:

Calculating a first transformation for alignment of a first pattern fora first layer based on measurement data for the first layer and ontransformation limitations of a first machine configured to write thefirst layer;

Calculating a second transformation for alignment of a second patternfor a subsequent layer based on a transformation type to be used for amachine configured to write the second layer;

Calculating a difference between first and second transformations andthen distributing the difference between first and secondtransformations;

Verifying that said adjusted first pattern is within alignmenttolerances for the first layer and/or the second layer, respectively;

Writing a pattern on the first and second layers according to therespective first and second compensated transformations.

Writing a pattern on the first and second layers according to therespective first and second compensated transformations.

Further optionally comprising embodiments:

wherein the distribution of the error comprises:

minimizing, in a parameter space of measurement data for the firstlayer, a total standard deviation for at least the first and secondtransformations in the radial domain.

wherein the distribution of the error comprises:

minimizing, in a parameter space of measurement data for the firstlayer, a maximum standard deviation for at least the first and secondtransformations.

wherein the distribution of the error comprises:

minimizing, in a parameter space of measurement data for the firstlayer, a maximum error for at least the first and secondtransformations.

Distribution of Errors Between a Series of Layers

In another embodiment the problem of alignment accuracy and overlayerror is addressed by optimizing a distribution of the alignment errorover a plurality of layers dependent on given boundary values. Anunderlying concept is to reserve a party of a total alignment budget forminimization of the difference in transformation for dies that shouldhave the same or a similar transformation. These embodiments of theinvention solve the problem aspect of meeting certain boundaryconditions on the surface layers, and may be applied on workpiece havingor not having embedded dies.

In the example as shown in FIG. 27 the boundary values may be given by aworkpiece 2702 with embedded dies with a first connecting layer LN thatshould be connected to solder bumps in a layer LN+3.

In the example as shown in FIG. 28 the boundary values may be given by aboundary condition 2802 e.g. set by another workpiece with a firstconnecting layer LN that should be connected to solder bumps in a layerLN+3.

For the optimization, a priori information is needed for the boundaryvalues, preferably there should be a priori information at hand aboutthe number of layers that is available for distribution of the error.Further, there should preferably be available information about therequired layer-to-layer tolerances for each layer. The optimization ispreferably conducted such that a large part of the compensation isdistributed to a low end layer having less strict or lower requirementson alignment, i.e. lower requirements on layer-to-layer-tolerance.

For example, if the total alignments requirement is X micrometers(adjustment) and the machine that performs the patterning has analignment performance of 0.5*X micrometers, it is possible to consume(1-0.5)*X micrometers for each layer in order to compensate for thedifference in alignment transformation in-between dies.

FIG. 24A-24C illustrates patterns associated with dies for differentlayers. FIG. 24A illustrates dies 2408, 2406, 2410 that are distributedin a first layer L1 of a workpiece 2402. The form of lines indicatingthe respective different dies are used throughout FIG. 24A to 24C. FIG.24B illustrates the pattern for a second layer L2 and FIG. 24Cillustrates the pattern for an Nth layer LN on a workpiece 2402. FIG. 25illustrates how patterns in different layers associated to a respectivedie on a workpiece 2402 get progressively better aligned for each layerL1, L2, L3, L4.

FIG. 27 part B illustrates how each of the patterns 2712 are compensatedtowards the boundary value given by the solder bump 2710. With thesuccessive compensation of the patterns in layers LN+1 to LN+3 a closedconnection path is created between the die 2704 and solder bump 2710.

FIG. 28 part B illustrates how each of the patterns 2712 are compensatedtowards the boundary value given by the solder bump 2710. With thesuccessive compensation of the patterns in layers LN+1 to LN+3 a closedconnection path is created between the first boundry value 2802 andsolder bump 2710.

The transformation correction can be evenly spread for each layer wereit is possible to do a compensation or it can be distributed in a sensethat reflects how critical each layer is. It is also possible to dividethe correction arbitrary or use some other predetermined rules. Thechoice of reference that the correction term shall be calculated fromcan for example be chosen as the nominal orthogonal coordinate system,the mean between the transformation of dies in same group or a arbitrarylinear combination of them or some other arbitrary reference that makesense. A linear or non linear transform can also be fitted to eachtransform in one group in order to create a reference, (boundarycondition), see FIG. 26. FIG. 26 illustrates a reference positionRG1,RG2 for each group G1,G2 of respective die group DG1,DG2.

For example, the correction for each die in each layer can be calculatedas:Min(allowedCorrection,DeviationFromReference/NumberOfLayers);

AllowedCorrection=maximum allowed compensation for each layer in ordernot to violate the alignment requirement for each layer;

DeviationFromReference=Deviation from die position compared to thedesied position, can be multiple of values for each die, either an XYmatrix or vector or global parameters such as translation, rotation etc;

NumberOfLayers=Number of layers were it is possible to make corrections.

The distribution of the error may comprise distributing the correctionof the error according to a predefined distribution rule among thecompensated transformations for a plurality of layers.

The distribution rule for the distribution of the error comprises aselection of evenly or arbitrarily distributing the correction of theerror among the compensated transformations.

The compensated transformation is calculated with reference to aselection of: the nominal coordinate system of the original circuitpattern data; or the mean between the transformation of dies in aselected group of dies.

Further Embodiments of Distribution of Errors Between a Series of Layers

Embodiments for distribution of errors between a series of layerscomprises the following variations.

A method of patterning a plurality of layers of a workpiece in a seriesof writing cycles in one or a plurality of write machines, the workpiecebeing devised to have a number of N+2 (N>1) layers and layers of theworkpiece having one or a plurality of boundary condition(s) for patternposition locally and globally in relation to some reference e.g. to atleast one other workpiece or electrical component,

the method comprising the steps of:

-   Receive a priori information about the boundary conditions of layers    1 and N+2;-   Calculating the deviation between a perfect fit between a pattern of    layer 1 and a pattern of layer N+2 due to the boundary conditions;-   Distributing the deviation between the layers 2 to N+1 assigning a    selectable part of the deviation to each respective layer;-   Writing the first layer according to boundary condition of layer 1-   Aligning the second pattern, i.e. the pattern that is a currently    written, including calculating a transformation for fitting the    second pattern to the first layer;-   Adding the assigned deviation for the second layer to the calculated    transformation (step e).-   Adjusting the second pattern according to the adjusted    transformation (step f);-   Verifying that said adjusted second pattern is within alignment    tolerances for the second layer;-   Writing, if positively verified, said adjusted second pattern on    said first layer.-   Repeat e-i for the N−1 layers;-   Write the N+2 layer according to boundary condition of layer N+2

Further optionally comprising a selection of embodiments:

where the boundary condition can cover the whole surface or part of thesurface of the workpiece.

where the boundary condition is set by an internal layer in theworkpiece.

where the boundary condition can be a combination of claims 2 and 3.

wherein the boundary condition is:

-   -   local or global; or    -   a compensation for an individual die; or    -   for a subarea within a die; or    -   for an individual zone on the workpiece; or    -   for the whole workpiece.

wherein a number N of layers are to be patterned, N being an integer >1.

wherein the step of calculating the transformations is performed in analignment procedure.

wherein the distribution of the deviation is based on:

-   -   predetermined distribution rules; or    -   an analysis of the level of requirements for alignment accuracy.        wherein the selectable part of the difference in deviation is        selected as:    -   the difference in deviation divided by the number of subsequent        layers;    -   the whole difference in deviation, for example when a high level        of accuracy in alignment is required.        wherein the boundary condition may be that:    -   a different write machine will write the subsequent layer N+1,        for example a via machine; or that    -   the subsequent layer N+1 is a layer for which only a specific        type of transformation may be used, for example a solder layer.

wherein:

-   -   at least one layer of the work piece having a plurality of dies        distributed thereon;    -   each die being associated with an original circuit pattern and        being represented by original circuit pattern data;    -   each die being associated with measurement data of alignment        features of the respective layer.

wherein boundary conditions are given by embedded dies.

wherein a first and a second sets of boundary conditions are given whena first and a second workpieces are to be joined with a third workpiece.

wherein optimization by distribution of a deviation is performed inresponse to detecting that the deviation is outside alignment tolerancesfor a layer.

wherein the compensation in the adjusted pattern is:

-   -   local or global; or    -   a compensation for an individual die; or    -   for a subarea within a die; or    -   for an individual zone on the workpiece; or    -   for the whole workpiece.

Further an embodiment of a method of patterning a plurality of layers ofa work piece in a series of writing cycles in one or a plurality ofwrite machines,

-   -   at least one layer of the work piece having a plurality of dies        distributed thereon;    -   each die being associated with an original circuit pattern and        being represented by original circuit pattern data;    -   each die being associated with measurement data of alignment        features of the respective layer;        the method comprising the steps of:

-   Calculating a first transformation for alignment of a first pattern    for a first layer based on boundary conditions for alignment of said    first pattern in the first layer;

-   Calculating a second transformation for alignment of a second    pattern for a subsequent layer based on boundary conditions for    alignment of said second pattern in the second layer;

-   Calculating first and second compensated transformations    distributing the correction of an error in relation to the original    circuit pattern among the first and second compensated    transformations;

-   Writing pattern on the first and second layers according to the    respective first and second compensated transformations.

Further optionally comprising embodiments:

wherein the distribution of the error comprises:

distributing the correction of the error according to a predefineddistribution rule among the compensated transformations for a pluralityof layers.

wherein the distribution rule for the distribution of the errorcomprises a selection of:

evenly or arbitrarily distributing the correction of the error among thecompensated transformations.

wherein the boundary conditions are given by a workpiece having embeddeddies thereon and a subsequent layer being a solder layer to be writtenby means of a fixed photomask.

Optimization Embodiments

The methods of any of the preceding embodiments regarding alignmentoptimization with regard to a plurality of layers, may be combined withany of the above described embodiments in this text.

For example, such an embodiment comprises a method of patterning aplurality of layers of a work piece in a series of writing cycles in oneor a plurality of write machines,at least one layer of the work piecehaving a plurality of dies distributed thereon; each die beingassociated with an original circuit pattern and being represented byoriginal circuit pattern data; each die being associated withmeasurement data of alignment features of the respective layer; themethod comprising the steps of:

Calculating a first transformation for alignment of a first pattern fora first layer based on measurement data for the first layer and ontransformation limitations of a first machine configured to write thefirst layer;

-   a. Calculating a second transformation for alignment of a second    pattern for a subsequent layer based on a transformation type to be    used for a machine configured to write the second layer;-   b. Calculating first and second compensated transformations    distributing the correction of an error in relation to the original    circuit pattern among the first and second compensated    transformations.

In another example, an embodiment of the method comprises the steps of:Calculating a first transformation for alignment of a first pattern fora first layer based on boundary values for alignment of said firstpattern in the first layer;

-   -   a. Calculating a second transformation for alignment of a second        pattern for a subsequent layer based on boundary values for        alignment of said second pattern in the subsequent layer;    -   b. Calculating first and second compensated transformations        distributing the correction of an error in relation to the        original circuit pattern among the first and second compensated        transformations.

These embodiments may be applied together with a method for patterning alayer of a first workpiece in a direct write machine in themanufacturing of a multilayer stack, where the direct write machine isprovided with a coordinate system for controlling write operations on afirst layer of the first workpiece having a plurality of diesdistributed thereon, wherein the plurality of dies each have a pluralityof connection points. This embodiment comprises the steps of:

-   a. retrieving first circuit pattern data of a first circuit pattern    representing at least one first sub-area of said first layer of the    first workpiece, wherein the at least one first sub-area is    associated with, and is covering, at least one die of the plurality    of dies of the first layer;-   b. retrieving second circuit pattern data of a second circuit    pattern representing at least a second sub-area associated with a    plurality of connection points of one or a plurality of specific    features of a second layer(s), wherein the second layer(s) is one or    a plurality of preceding or succeeding layer(s) of the first    workpiece and/or one or a plurality of layer(s) in a second    workpiece that is to be connected to the first workpiece, and    wherein at least one of the plurality of connection points of the at    least one die of the first layer is adapted for connecting to at    least one of the connection points of the one or plurality of    specific features of the second layer(s);-   c. determining required first fitting tolerance(s) for adjusting the    first circuit pattern at least to the first sub-area of the first    layer;-   d. determining required second fitting tolerance(s) for adjusting    the first circuit pattern so that the connection points of the    adjusted first circuit pattern fit to the connection points of at    least one second circuit pattern representing the one or plurality    of specific features of the second layer(s);-   e. preparing adjusted first circuit pattern data that fit the    adjusted first circuit pattern to    -   i. the at least one first sub-area of the first layer within the        required first fitting tolerances; and    -   ii. the at least one of the connection points of the at least        one die of the first circuit pattern representing the at least        one first sub-area to the at least one of the connection points        of the one or plurality of specific features of the at least one        second circuit pattern within the second fitting tolerance(s);

Then a pattern is written on the first and second layers of the firstworkpiece according to the adjusted first circuit pattern data andaccording to the respective first and second compensatedtransformations.

The above embodiments may also be applied together with a method forpatterning a second layer of a work piece in a direct write machine inthe manufacturing of a multilayer stack, the work piece having a firstlayer with a plurality of electrical components in the form of dies thatare arbitrarily placed, each die having connection points whereof someare to be connected between the dies, a selection of said dies beingassociated with a first pattern wherein different zones comprisingconnection points of dies distributed in the first layer are associatedwith different requirements on alignment;

the method comprising the steps of:

-   a. detecting sacred zones in the first pattern that have a high    requirement on alignment to selected features of the stack or to the    placed dies;-   b. detecting stretch zones of the first pattern that are allowed to    have a lower requirement on alignment to other features of the    stack;-   c. transforming the first pattern by calculating adjusted first    pattern data comprising transformation of the original circuit    pattern such that:    -   i. connection points in adjacent sacred zones are aligned within        a pre-settable alignment deviation parameter;        -   and such that    -   ii. deviations between the positions of corresponding connection        points in the sacred zones are compensated for in the pattern        for connection points of the stretch zones;        Then a pattern is written on the layer of the work piece        according to the adjusted pattern data.

Further details of these embodiments are described under the respectivesections above.

Determining the Coordinate System and Performing Alignment withReference Board

The coordinate system in a write machine, such as direct writer in anLDI system, can be determined in different manners, for example bydetecting a reference scale or a reference board; or by structuralmechanisms such as the positions of cameras, the positions beingconsidered to be fixed; or by using light measurements such asinterferometrics.

In an example embodiment the determining of the coordinate system of awrite machine is carried out by means of a reference board in thefollowing setup. The reference board is applied in a writing system andan alignment system comprising a measurement station and a referenceboard mounted on a workpiece carrier stage. The alignment system thusincludes a measurement station with a camera bridge on which, in thisexample, a plurality of camera systems are mounted, and a referenceboard mounted on each of a plurality of workpiece carrier stages. Theremay be one or a plurality of cameras comprised in the measurementstation. The carrier stages move between measurement station of thealignment system and the writing system. A computer is operativelyand/or communicatively coupled to the measurement station of thealignment system and the writer system. In operation, typically aplurality of carrier stages are used to carry separate workpieces forpatterning. The carrier stages are typically displaceable on a carrierstage track between a measurement position in the measurement stationand a writing station in the writer.

A reference board is attached to each carrier stage. The reference boardmay for example be composed of a temperature stable material such as QZ(quartz). The reference board carries information between themeasurement station coordinate system of the alignment system and thewriter coordinate system.

The reference board is preferably attached to the carrier stage in sucha manner that the reference board is fixed to the carrier stage. Forexample, as in one embodiment, the reference board is fastened or joinedto the carrier stage by bolts or screws. Preferably, a joint would bearranged in combination with a flexural joint mechanism to compensatefor tensions for example due to temperature changes. In anotherembodiment, the reference board is glued to carrier stage.

Reference features, for example in the form of a grid pattern areprovided on the reference board. The reference features may comprisemarks constituting board reference features including circles in theform of filled circles and annular ring shaped circles. The positions ofthe marks are either known from a sufficiently accurate measurementmachine or written by equipment such that the marks are assumed to beideal. In one example application of the invention, the positions of themarks are measured, and the measured positions of the marks are comparedto nominal positions to create a compensation map. The compensation mapaddresses the residual error and is used in the alignment process tocreate an adjusted pattern.

In a more general sense, the reference board is implemented forassociating the reference features with the carrier stage by integratingthe reference features directly with the carrier stage. This is interalia used in a method for calibrating the alignment system.

The reference board can be used to determine the coordinate system of awrite machine in an alignment process. Such an alignment processdescribed in a general wording is typically applied in a setting whereina pattern generating tool according comprises a reference board attachedor fixed to a stage, the reference board being configured to carryalignment information between the alignment system and a writing tool.One or more cameras are mounted on a camera bridge, and the one or morecameras are configured to measure positions of alignment marks on asubstrate relative to the reference board, the substrate being attachedor fixed to the stage. A writing system is configured to expose thesubstrate. A computer is operatively coupled to the alignment system andwriter system.

The method comprises the steps of providing a reference board attachedto the carrier stage, the reference board having board referencefeatures on predetermined nominal positions; measuring at least once, inthe measurement station, the position, e.g. location and orientation, ofat least one of the reference features of the workpiece relative thereference board;displacing the carrier stage with the reference boardfrom the measurement station to the writing station; calibrating thewriting station by measuring the position of the reference board usingat least one of the board reference features of the reference board.

Further, the embodiments of the method comprise a selection of optionalcalibration steps. Firstly, the method may include the step ofcalibrating the writing station by measuring the position of thereference board using at least one of the board reference features ofthe reference board.

Secondly, the method may include the step of calibrating the measurementstation to the reference board by measuring, in the measurement station,at least one of the board reference features of the reference board.

The calibrating of the measurement station comprises, in one variationthe steps of: determining the scale error and distortion for each camerain the measurement station by measuring the positions of board referencefeatures arranged in a uniform or non uniform grid pattern on thereference board and comparing with nominal positions of the boardreference features;

calculating a lens distortion map dependent on the measured scale errordistortions of the cameras;, the map can hold only the non linear scaleerrors/distortions or also the global linear scale error.

calculating the landing angle of the camera by measuring position ofreference boards at different height;determining the position of eachcamera in the measurement station relative the reference board by:detecting the position of board reference features on the referenceboard; calculating the position of each camera dependent on apredetermined relationship between the position of the board referencefeatures and a reference point on the reference board; calculating therotation of each camera as the rotation between the pattern and thecoordinate system associated with the camera.

The calibration of the write machine and optionally also the measurementsystem is thus advantageously used for determining the coordinate systemof the write machine.

When patterning and aligning according to various embodiments asdescribed above, this may be carried out using a reference boardaccording to the following method:

A method of patterning a layer of a workpiece in a write machine, wherethe write machine comprises:

-   -   a pattern writing station provided with a write machine        coordinate system; and    -   a measurement station provided with a measurement coordinate        system, the measurement station being configured to perform        measurements of objects on a workpiece associated with reference        features, where the workpiece is further placed on a carrier        stage and where the write machine is configured to displace the        carrier stage between the measurement station and the writing        station;    -   the method comprising the steps of:        -   a. providing a reference board attached to the carrier            stage, the reference board having board reference features            on predetermined nominal positions;        -   b. measuring at least once, in the measurement station, the            position, e.g. location and orientation, of at least one of            the reference features of the workpiece relative the            reference board;        -   c. calculating a transformation dependent on both the            measured reference position(s) and on the nominal            position(s) of the reference feature(s) of the workpiece,            the transformation describing the deviation of the measured            positions from the nominal position(s);        -   d. displacing the carrier stage with the reference board            from the measurement station to the writing station;        -   e. writing the pattern on the workpiece by adjusting for the            transformation describing the deviation of the measured            position(s) from the nominal position(s).            -   The alignment method may further include the step of                calculating a transformation comprises:            -   the action of calculating adjusted pattern data                according to the transformation, and            -   fitting the adjusted pattern data to the position of the                workpiece being given relative the position of the                reference board;            -   and wherein:            -   the step of writing the pattern on the workpiece is                performed by exposing the work piece according to the                adjusted pattern data.            -   Further embodiments are developed wherein:            -   the calculation of the adjusted pattern data for writing                on the work piece is dependent on measured positions of                the reference features of the work piece relative a                board reference feature of the reference board, and                wherein the reference board represents the coordinate                system of the carrier stage by having a attached                relative distance to the carrier stage.            -   The method further comprising the step of calibrating                the writing station by measuring the position of the                reference board using at least one of the board                reference features of the reference board.            -   The method further comprising the step of calibrating                the measurement station to the reference board by                measuring, in the measurement station, at least one of                the board reference features of the reference board.            -   A carrier stage for use in a write machine configured                for patterning of a layer of a workpiece, wherein                reference features are associated with the carrier                stage, the reference features having predetermined                nominal positions.

The carrier stage for this purpose comprises a reference board isattached to the carrier stage, the reference board having boardreference features on predetermined nominal positions. The referencefeatures and/or the reference board is configured with an orientation onthe carrier stage:—orthogonally in relation to the main movementdirection of the reference board; and/or—coaxially in relation to themain movement direction of the reference board. The reference featuresand/or the reference board may for example be configured: in an elongateshape;—in an L-shape, and wherein the reference board for example isattached to the carrier stage by:—a screw or bolt joint;—a glue joint.

The invention claimed is:
 1. A method of patterning a plurality oflayers of a workpiece in a series of writing cycles in one or aplurality of write machines, applied when writing a first pattern on afirst layer N of the workpiece, wherein a boundary condition for theavailable accuracy in fitting a second pattern for a subsequent layerN+1 to the first layer is determined; the method comprising the stepsof: a. Receiving a priori information about the limitation in performinga limited transformation of the second pattern for said subsequent layerN+1; b. Calculating: i. a best fit transformation of the first patternfor the first layer N that renders a best fit to a preceding layer N−1using alignment transformation available for writing on the first layerN, and ii. the deviation between a perfect fit and the best fittransformation; c. Calculating: i. a limited transformation applied intransforming the second pattern for the second layer N+1 to fit theorientation to said preceding layer N−1, d. Calculating the differencein the deviation between said best fit transformation and said limitedtransformation; e. Calculating a compensation of the best fittransformation by adding a selectable part of said difference indeviations; f. Calculating an adjusted first pattern comprising saidcompensation; g. Verifying that said adjusted first pattern is withinalignment tolerances for the first layer N: h. Writing, if positivelyverified, said adjusted first pattern on said first layer N.
 2. Themethod of claim 1, wherein a number N of layers are to be patterned, Nbeing an integer >1.
 3. The method of claim 1, wherein the best fit andlimited transformations are calculated in an alignment procedure.
 4. Themethod of claim 1, wherein the limitation in performing the limitedtransformation is estimated.
 5. The method of claim 1, wherein theselectable part of the difference in deviations is selected as: thewhole difference in deviation.
 6. The method of claim 1, wherein theselectable part of the difference in deviations is selected such thatthe difference in deviations is distributed locally between subsets oflayers.
 7. The method of claim 1, wherein: a. a plurality of datacollections each representing an individual pattern transformation isseparately resampled and stored in a bitmap format; b. resampling thedata collection(s) to fit the pattern of a layer in the step ofcalculating an adjusted first pattern; and c. optionally merging aselection of the data collections into a single data collection, beforeor after step b.
 8. The method of claim 1, wherein a distribution of thedifference in deviations comprises: minimizing, in a parameter space ofmeasurement data for the first layer N, a total standard deviation forat least the best fit transformation and the limited transformation inthe radial domain or using Euclidian norm.
 9. The method of claim 1,wherein a distribution of the difference in deviations comprises:minimizing, in a parameter space of measurement data for the first layerN, a maximum standard deviation for at least the best fit transformationand the limited transformation.
 10. The method of claim 1, wherein adistribution of the difference in deviations comprises: minimizing, in aparameter space of measurement data for the first layer N, a maximumerror for at least the best fit transformation and the limitedtransformation.
 11. The method of claim 1, wherein the boundarycondition is such that: a different write machine will write thesubsequent layer N+1; or the subsequent layer N+1 is a layer for whichonly a specific type of transformation is used.
 12. The method of any ofclaim 1, wherein: at least one layer of the workpiece has a plurality ofdies distributed thereon; each die is associated with an originalcircuit pattern and is represented by original circuit pattern data; andeach die is associated with measurement data of alignment features ofthe respective layer.
 13. The method of claim 1, further comprising thestep of: minimizing errors from layer to layer.
 14. A method ofpatterning a plurality of layers of a workpiece in a series of writingcycles in one or a plurality of write machines, at least one layer ofthe workpiece having a plurality of dies distributed thereon; each diebeing associated with an original circuit pattern and being representedby original circuit pattern data; each die being associated withmeasurement data of alignment features of the respective layer; themethod comprising the steps of: c. Calculating a first transformationfor alignment of a first pattern for a first layer based on measurementdata for the first layer and on transformation limitations of a firstmachine configured to write the first layer; d. Calculating a secondtransformation for alignment of a second pattern for a subsequent layerbased on a transformation type to be used for a machine configured towrite the second layer; e. Calculating a difference between first andsecond transformations and then distributing the difference betweenfirst and second transformations by minimizing, in a parameter space ofmeasurement data for the first layer, a total standard deviation for atleast the first and second transformations in the radial domain; f.Verifying that said adjusted first pattern is within alignmenttolerances for the first layer and/or the second layer, respectively; g.Writing a pattern on the first and second layers according to therespective first and second compensated transformations.
 15. The methodof claim 14, wherein the distributing of the difference between firstand second transformations comprises: minimizing, in the parameter spaceof measurement data for the first layer, a maximum standard deviationfor at least the first and second transformations.
 16. The method ofclaim 14, wherein the distributing of the difference between first andsecond transformations comprises: minimizing, in the parameter space ofmeasurement data for the first layer, a maximum error for at least thefirst and second transformations.
 17. The method of claim 5, wherein theselectable part of the difference in deviations is selected as the wholedifference in deviation when a high level of accuracy in alignment isrequired.
 18. The method of claim 6, wherein the difference indeviations is distributed locally between subsets of layers such thatthe difference in deviation for a first subset of pattern is compensatedfor in the first layer N and the difference in deviation for a secondsubset of the pattern is compensated for in the second layer N+1. 19.The method of claim 11, wherein the different write machine is a viamachine, and the subsequent layer N+1 is a solder layer.
 20. The methodof claim 13, wherein the minimizing errors from layer to layer isapplied on a workpiece having or not having embedded dies.